Merge branch 'release/0.4.1' into develop
Gracefully handle our old JSON format in the gui too
Optimize our filter initialization code
Use the logging module in the filters
Handle keyboard interrupts in the gui
Fix a typo in a comment
Utilize Twisted's reactor.callInThread to speed up filter initialization.

This allows filters to perform slow queries without blocking the daemon from
processing new messages.
Only traverse the abrt crash directory if it exists.
Create ~/.cache/fedmsg-notify if it doesn't exist
Utilize Twisted Deferreds so we don't block while downloading icons.
Make the msg repr an INFO log
Use tempfile.mkdtemp for our icon cache instead of ~/.cache

• This lets us take advantage of the 10d max age of /tmp defined by
  /usr/lib/tmpfiles.d/tmp.conf

• Since /tmp is on tmpfs we avoid having to grab both icons from disk for
  every single message (I have no idea if the shell caches them for us).
Hash the icons to avoid caching duplicates
Call __del__ atexit to ensure our cache gets cleaned up.
Unlink duplicate icons if their checksum is already in our cache
Link up each of the text processors and add descriptive tooltips
Update the copyright
Bump version to 0.5.0
Merge branch 'release/0.5.0'