Refactored the mercurial plugin which led to new vcsbase common
tools (VCSBaseClient, VCSBaseClientSettings and VCSJobRunner)
Merge-request: 229
Reviewed-by: Tobias Hunger <tobias.hunger@nokia.com>
Start the jobrunner on demand, save options only if changed,
give it the structure used elsewhere in the VCS plugins. Remove
last traces of the cmd /c hack.
Do not use "cmd /c hg" on Windows as this will fail randomly
depending on arguments with blanks, such as "-U 8". Output log
messages about synchronous commands, format author correctly,
label menus correctly.
