UTF8 support

[gyscos]

This bot doesn't seem to properly encode utf-8 content.
I posted 😁 in a svn commit message (which is correctly parsed by other SVN clients), but the hook sent this to slack: ?\240?\159?\152?\129.

Our jenkins setup correctly parsed the svn commit, and also sent a slack message, with proper formatting. So both SVN and slack correctly handle this, but not the svn hook from this repository.

[digason]

@gyscos I did some experimenting with forcing the Perl script to send as UTF-8, and after doing so, my suspicion is that the Subversion Slack app (https://obiwebdev.slack.com/apps/A0F827LTA-subversion) isn't processing UTF-8 content properly.