Update README.md

Updated the README with new informations about the optional parameters. And the known Issues.
Remove the Podspec out of the repository. This don't belong in here and is a part of the CocoaPods Specs and not the project itself.
Merge branch 'master' of https://github.com/mRs-/KNSemiModalViewController
Removed the shadow path for better landscape support
Merge pull request #31 from mRs-/master

Clean Up for Landscape Shadow Support