Fixed bin and obj folders to support silverlight-style capitalization, and...

Fixed bin and obj folders to support silverlight-style capitalization, and added the trailing slash, so that Git treats these entries as directory entries.

CSharp.gitignore

 # Build Folders (you can keep bin if you'd like, to store dlls and pdbs)
-bin
-obj
+[Bb]in/
+[Oo]bj/
 
 # mstest test results
 TestResults
\ No newline at end of file