Aka: add 'list' command (Closes ProgVal/Limnoria#572)
Aka: update listCommands override to only include built in cmds

The old behavior is superseded by 'aka list'. This makes it easier for people to find Aka plugin's core commands, as
'list Aka' won't be filled with random, irrelevant alias definitions.
Aka: update tests
Aka: catch with error if 'aka list' response is empty
Aka: update list command
Aka: update converters to use 'channel' instead of 'somethingWithoutSpaces'
Merge branch 'testing' into aka-2

Conflicts:
	plugins/Aka/plugin.py
Revert "Aka: update converters to use 'channel' instead of 'somethingWithoutSpaces'"

This reverts commit 231c250b75357988cdc48ab91656c3043f9fdcec.
Aka: add a missing '.' in the error message
Merge pull request #952 from GLolol/aka-2

Aka: add 'list' command & update listCommands override