Adding exceptions and fixing comments

Added a InvalidDeveloperKey exception. Documented with comments. It will
be thrown in the contructor of the base parameters if the parameter key
is not valid.
Fixing conflicts
Merge remote-tracking branch 'origin/master'

Conflicts:
	SteamdotNet/SteamdotNet.v11.suo
	SteamdotNet/bin/Debug/SteamdotNet.XML
	SteamdotNet/bin/Debug/SteamdotNet.dll
	SteamdotNet/bin/Debug/SteamdotNet.pdb