Add new jobs for jenkins

This is for issue #24, I added just jobs for desktop, for mobile if we decide we want to run them to we can just copy the job and add an extra parameter in xshell command. 
Regarding trigger.py, I added just a  plain script with options so it won't throw when called, this will be overwrited by upcoming pr from issue #17.
I know how to treat boolean values, see `--igonre-unused-engines`, I made this decision because we want to treat the presence of the boolean value from jenkins job variables. Otherwise we would have to append the option in to the xshell command, and we don't have a clean way to do that.
We had this issue on mozmill-automation issue #132 while handling `--override-update-settings` option
 https://github.com/mozilla/mozmill-automation/pull/133/files