Revert "version 0.1.7 for bump to chrono 0.4.0"

This reverts commit 1d7d82b4d09d7f40f8fc6bc1714fd63c69ccb190.
diff --git a/Cargo.toml b/Cargo.toml
index 71fe7e7..1a0bbb9 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "tuf"
-version = "0.1.7"
+version = "0.1.6"
 authors = [ "heartsucker <heartsucker@autistici.org>" ]
 description = "Library for The Update Framework (TUF)"
 homepage = "https://github.com/heartsucker/rust-tuf"
@@ -30,7 +30,7 @@
 cli = [ "clap" ]
 
 [dependencies]
-chrono = { version = "0.4", features = [ "serde" ] }
+chrono = { version = "0.3.1", features = [ "serde" ] }
 clap = { version = "2.23", optional = true }
 data-encoding = "2.0.0-rc.1"
 env_logger = "0.4.3"
diff --git a/src/metadata.rs b/src/metadata.rs
index 6056b94..7d77a93 100644
--- a/src/metadata.rs
+++ b/src/metadata.rs
@@ -1,5 +1,4 @@
-use chrono::DateTime;
-use chrono::offset::Utc;
+use chrono::{DateTime, UTC};
 use data_encoding::HEXLOWER;
 use json;
 use pem;
@@ -134,14 +133,14 @@
 }
 
 pub trait Metadata<R: RoleType>: DeserializeOwned {
-    fn expires(&self) -> &DateTime<Utc>;
+    fn expires(&self) -> &DateTime<UTC>;
 }
 
 
 #[derive(Debug, PartialEq)]
 pub struct RootMetadata {
     consistent_snapshot: bool,
-    expires: DateTime<Utc>,
+    expires: DateTime<UTC>,
     pub version: i32,
     pub keys: HashMap<KeyId, Key>,
     pub root: RoleDefinition,
@@ -151,7 +150,7 @@
 }
 
 impl Metadata<Root> for RootMetadata {
-    fn expires(&self) -> &DateTime<Utc> {
+    fn expires(&self) -> &DateTime<UTC> {
         &self.expires
     }
 }
@@ -272,14 +271,14 @@
 
 #[derive(Debug, Clone)]
 pub struct TargetsMetadata {
-    expires: DateTime<Utc>,
+    expires: DateTime<UTC>,
     pub version: i32,
     pub delegations: Option<Delegations>,
     pub targets: HashMap<String, TargetInfo>,
 }
 
 impl Metadata<Targets> for TargetsMetadata {
-    fn expires(&self) -> &DateTime<Utc> {
+    fn expires(&self) -> &DateTime<UTC> {
         &self.expires
     }
 }
@@ -334,13 +333,13 @@
 
 #[derive(Debug)]
 pub struct TimestampMetadata {
-    expires: DateTime<Utc>,
+    expires: DateTime<UTC>,
     pub version: i32,
     pub meta: HashMap<String, MetadataMetadata>,
 }
 
 impl Metadata<Timestamp> for TimestampMetadata {
-    fn expires(&self) -> &DateTime<Utc> {
+    fn expires(&self) -> &DateTime<UTC> {
         &self.expires
     }
 }
@@ -382,13 +381,13 @@
 
 #[derive(Debug)]
 pub struct SnapshotMetadata {
-    expires: DateTime<Utc>,
+    expires: DateTime<UTC>,
     pub version: i32,
     pub meta: HashMap<String, SnapshotMetadataMetadata>,
 }
 
 impl Metadata<Snapshot> for SnapshotMetadata {
-    fn expires(&self) -> &DateTime<Utc> {
+    fn expires(&self) -> &DateTime<UTC> {
         &self.expires
     }
 }
diff --git a/src/tuf.rs b/src/tuf.rs
index 6dadb03..8b666e4 100644
--- a/src/tuf.rs
+++ b/src/tuf.rs
@@ -1,4 +1,4 @@
-use chrono::offset::Utc;
+use chrono::UTC;
 use json;
 use hyper::Url as HyperUrl;
 use hyper::client::Client;
@@ -217,7 +217,7 @@
 
         // handle the edge case where we never enter the update look
         // AND the first piece of metadata is expired
-        if temp_root.version == 1 && self.root.expires() <= &Utc::now() {
+        if temp_root.version == 1 && self.root.expires() <= &UTC::now() {
             return Err(Error::ExpiredMetadata(Role::Root));
         }
 
@@ -595,7 +595,7 @@
         Self::verify_meta::<R>(signed.clone(), role, threshold, trusted_ids, available_keys)?;
         let meta: M = json::from_value(signed.signed)?;
 
-        if !allow_expired && meta.expires() <= &Utc::now() {
+        if !allow_expired && meta.expires() <= &UTC::now() {
             return Err(Error::ExpiredMetadata(role.clone()));
         }