Fix ICE component count bug in mochitest.

Code was counting number of succeeded candidate pairs in the stats, but
it is easy to have multiple succeeded pairs per component. Now counts
selected pairs. Also, changed some naming.
Disable unneeded ICE components, and fix a duplicate candidate bug.

When answerer between SetRemote and SetLocal, we were buffering remote
candidates both in the remote SDP, and a buffer in PCMedia. When
offer/answer concluded, these candidates were added twice, which was
confusing the mochitests.
Merge pull request #228 from docfaraday/disable_unneeded_ice_components

Disable unneeded ice components