[version] Use actual version number when asking for version

i.e. CTCP and .version. CTCP VERSION no longer gives commit data, .version will give it if available.
[core] Update version number in __init__ to 3.1.2
[info] Remove .stats command
[core] Remove willie.stats
[find] Use willie.memory to solve issue #163

Also, generally clean up the code a bit
[version] Fix error in CTCP reply
[find] Fix error when suggestiong a correction to unknown user

Issue #170
Merge branch 'master' of https://github.com/embolalia/willie