Consider switching to async mode in trigger

[pavelsher]

Seems this trigger can open connection to a gerrit server right from the triggerBuilds method. This is highly undesirable because it will slowdown processing of triggers on the entire server.

With this type of triggers some async operation mode is required. Please have a look at URL trigger source code as an example: https://svn.jetbrains.org/teamcity/plugins/url-build-trigger/trunk/