[Command] default to install

Closes #958

CHANGELOG.md

@@ -36,6 +36,9 @@ To install or update CocoaPods see this [guide](http://docs.cocoapods.org/guides
   submit a pull-request that adds the prefix of that manager
   [here](https://github.com/CocoaPods/CocoaPods/blob/master/bin/sandbox-pod#L40)._
 
+* The naked `pod` command now defaults to `pod install`.
+  [#958](https://github.com/CocoaPods/CocoaPods/issues/958)
+
 * Documentation generation has been removed from CocoaPods as it graduated
   to CocoaDocs. This decision was taken because CocoaDocs is a much better
   solution which doesn't clutter Xcode's docsets while still allowing

lib/cocoapods/command.rb

@@ -21,6 +21,7 @@ module Pod
     require 'cocoapods/command/podfile_info'
 
     self.abstract_command = true
+    self.default_subcommand = 'install'
     self.command = 'pod'
     self.description = 'CocoaPods, the Objective-C library package manager.'