added various plugins, modified metacritic & lastfm

added additional plugins for siri:

* leafly -- invoked with .leafly or .weed, gets a given strain of marijuana from Leafly.com and outputs details on it.
* goatkcd -- invoked with .goatkcd or .xkcd, gets a random goatkcd.com comic. if given a comic number, will output that comic if it can be found. also has sfw option for goatkcd's sfw comic.
* giantbomb -- invoked with .giantbomb or .gb, gets the first result from giant bomb's search api. if video, returns youtube url as well if exists and if game, returns review score + reviewer if exists
* twitch -- invoked with .twitch (.tw used by twitter.py), has a number of options as detailed in the help (no autohelp)
* soundcloud -- invoked with .soundcloud or .sc, returns the first search result for the given input or the first user found with the given name if "user" is a parameter
* metacritic -- fixed to allow for xbone/ps4 and to show scores (broken in current version). metacritic uses xone so added check for xbone as an alias
* lastfm - modified to return last.fm details about a given user or compare two users. current lastfm functionality moved to nowplaying
* nowplaying - invoked with .nowplaying or .np, gets current song scrobbled to last.fm for the given user. will store nick/user combinations so that no parameters have to be given in the future