fix 'pod trunk push' commands

must push one spec at a time, and if more than one exists,
must specify them by name.

Also include the 'LICENSE' file in the portable zip and let
SwiftLint.podspec know about it.

SwiftLint.podspec

@@ -3,7 +3,7 @@ Pod::Spec.new do |s|
   s.version        = `make get_version`
   s.summary        = 'A tool to enforce Swift style and conventions.'
   s.homepage       = 'https://github.com/realm/SwiftLint'
-  s.license        = 'MIT'
+  s.license        = { :type => 'MIT', :file => 'LICENSE' }
   s.author         = { 'JP Simard' => 'jp@jpsim.com' }
   s.source         = { :http => "#{s.homepage}/releases/download/#{s.version}/portable_swiftlint.zip" }
   s.preserve_paths = '*'