Since we want to do conditional linking, the list of Pods to link with 
needs to be provided by an xcconfig file. Only way to do that is to
remove the linking responsibility from Xcode and give it to ld directly.

https://github.com/lookback/Core/commit/affbeae85bd179c5e9a9a927a80f2aacc4d7cf7c
defines a new ":configurations" option for a pod, and exposes the corresponding
API. Using that API in include_in_build_config now lets aggregate_xcconfig
only include the build flags for the libraries that are used.

Next step is to make CocoaPods link using build flags, so that linking
can be disabled with an xcconfig.

Also fixes some typos from previous commit. Different xcconfigs are now
actually generated, correctly assigned, and it all builds! Doesn't pass
tests and all xcconfigs are still identical, but still: getting there!

This is not even nearly functional, I'm just prodding pieces of code to
see how it works.

Those bades look much nicer than the PNG badges on retina displays.

Add test for lint failures

Updated guidelines on submitting feature requests

Improve the lockfile version warning message

Correct a typo and improve the warning message that's shown when the
lock file was created with a newer version of CocoaPods.

Add tests for the spec edit command

Clarify author documentation and template

See https://github.com/CocoaPods/Xcodeproj/commit/0704b7772370feb8be154ace0ce48e09f215aeaf.

Merge branch 'newcommandspec' of https://github.com/carsonmcdonald/CocoaPods into carsonmcdonald-newcommandspec

Conflicts:
	spec/spec_helper/user_interface.rb

README update to refer to guides.