Add translate plugin

This relies on the TextBlob module being available.
Make translate print to stdout instead of calling reply
Add on_help method to translate plugin
Fix missing closing quotes in translate help message
Add tee plugin

This can be used to print intermediate results in a pipe.
Example: echo foo | tee | crypto b64 encode | tee | sendto bar
produces
> foo
> Zm9v
> bar: Zm9v
Merge pull request #17 from Cyanogenoid/tee

Add tee plugin
Merge pull request #16 from Cyanogenoid/translate

Add translate plugin, close #9