fix(flows): save Token properly

The installed flow didn't explicitly set the retrieved token
absolute, which would cause failures down the road.

Cargo.lock

@@ -1,6 +1,6 @@
 [root]
 name = "yup-oauth2"
-version = "0.5.6"
+version = "0.6.0"
 dependencies = [
  "chrono 0.2.22 (registry+https://github.com/rust-lang/crates.io-index)",
  "getopts 0.2.14 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -15,7 +15,7 @@ dependencies = [
  "serde_macros 0.7.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "syntex 0.32.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "url 0.5.9 (registry+https://github.com/rust-lang/crates.io-index)",
- "yup-hyper-mock 1.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "yup-hyper-mock 1.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -505,7 +505,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "yup-hyper-mock"
-version = "1.3.2"
+version = "1.3.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "hyper 0.9.5 (registry+https://github.com/rust-lang/crates.io-index)",

src/common.rs

@@ -117,7 +117,7 @@ impl Token {
 
     /// Returns a DateTime object representing our expiry date.
     pub fn expiry_date(&self) -> DateTime<UTC> {
-        UTC.timestamp(self.expires_in_timestamp.unwrap(), 0)
+        UTC.timestamp(self.expires_in_timestamp.expect("Tokens without an absolute expiry are invalid"), 0)
     }
 
     /// Adjust our stored expiry format to be absolute, using the current time.

src/installed.rs

@@ -139,14 +139,15 @@ impl<C> InstalledFlow<C> where C: BorrowMut<hyper::Client>
 
         // Successful response
         if tokens.access_token.is_some() {
-            let token = Token {
+            let mut token = Token {
                 access_token: tokens.access_token.unwrap(),
                 refresh_token: tokens.refresh_token.unwrap(),
                 token_type: tokens.token_type.unwrap(),
                 expires_in: tokens.expires_in,
                 expires_in_timestamp: None,
             };
-
+            
+            token.set_expiry_absolute();
             Result::Ok(token)
         } else {
             let err = io::Error::new(io::ErrorKind::Other,