Update version 1.48.0 => 1.49.0

Features:

* #1757 Allows injecting System.Net.Http.HttpMessageHandler when creating Google.Apis.Http.ConfigurableHtppClient.
* #1749 and #1753 Includes more detailed error information in batch operations.
* #1741 Alloes parameter validation to be bypassed.
* #1710 Makes obtaining default credentials more async (when possible).
* #1665 Adss support for GCE_METADATA_HOST environment variable.

Author: amanda-tarafa

Src/Support/CommonProjectProperties.xml

@@ -2,7 +2,7 @@
 
   <!-- common nupkg information -->
   <PropertyGroup>
-    <Version>1.49.0</Version>
+    <Version>1.50.0</Version>
     <Authors>Google Inc.</Authors>
     <Copyright>Copyright 2017 Google Inc.</Copyright>
     <PackageTags>Google</PackageTags>

features.json

@@ -1,8 +1,8 @@
 {	
   "language": "csharp",	
   "description": "C# libraries for Google APIs.",	
-  "releaseVersion": "1.49.0", "comment1": "Version of generated package.",	
-  "currentSupportVersion": "1.49.0", "comment2": "Version of support library upon which to depend.",	
+  "releaseVersion": "1.50.0", "comment1": "Version of generated package.",	
+  "currentSupportVersion": "1.50.0", "comment2": "Version of support library upon which to depend.",	
   "pclSupportVersion": "1.25.0", "comment3": "Version of PCL support library.",	
   "net40SupportVersion": "1.10.0", "comment4": "Version of net40 support library.",