Bug 994707 - Fix crash reporter writing submission events with CRLF line endings on windows. r=bsmedberg

This introduces a new argument to UIOpenWrite to open the file in binary
mode. We now write the submission events in binary mode so that LF
characters will not be translated to CRLF on Windows.

--HG--
extra : rebase_source : 828d593503960c77bcb6baee69d23161c838d3f6