Moved mtrlogobserver module to buildbot.steps.mtrlogobserver

Renamed buildbot.process.mtrlogobserver module to
buildbot.steps.mtrlogobserver. The mtrlogobserver.MTR is a step,
so having it under buildbot.steps make more sense.
added unit tests on mtrlogobserver.EqConnectionPool class
Merge branch 'mtrlogobserver' of git://github.com/elmirjagudin/buildbot