Fix patch application WRT windows line endings.

Fix patch application WRT windows line endings.

Previously the result of an application would have been \r\r\n in the
case of windows line endings, as RawText does not touch the \r, and
ApplyCommand adds "\r\n" if this is the ending of the first line in the
target file. Only always adding \n should be ok, since \r\n would be the
result if the file and the patch include windows line endings.

Also add according test.

Change-Id: Ibd4c4948d81bd1c511ecf5fd6c906444930d236e