Fixes the reading of dependencies that have spaces in their subspecs' name from Lockfiles

Closes https://github.com/CocoaPods/CocoaPods/issues/2850.
Should've been done with https://github.com/CocoaPods/Core/pull/179.

See http://regexr.com/39uen.
Btw, not sure if you knew about this, but you can have [comments in regex](http://www.ruby-doc.org/core-1.9.3/Regexp.html#class-Regexp-label-Free-Spacing+Mode+and+Comments).