fix RSSParser
fix metadata injector
make FastI2I error messages more accurate
change metadata injector log level
add mid for candidates in debug frame

Conflicts:
	Tribler/Main/vwxGUI/DispersyDebugFrame.py
add debug prints for metadata bot
add debug command (print communities) for metadata bot
fix metadata injector
refactory a bit
Merge pull request #888 from LipuFei/fix_rssparser

fix rssparser and metadata injector