Jenkins: Scripts for Building with Jenkins

This contains a number of new scripts to build in Jenkins. It's beta, but the first build went through. :-)

Basically it's a refactoring of the CI scripts we used to have before, however now everything is version controlled. Before, parts were buried in Electric Commander and had funny cross-dependencies with Perl scripts inside EC as well. Have a look into the `README` to learn how it works. In short: Jenkins controls the scripts with a small number of environment variables while it only calls this from the web interface:
```
ci/jenkins/cleanup.sh
ci/jenkins/build.sh
ci/jenkins/install.sh
ci/jenkins/quick_test.sh
ci/jenkins/publish.sh
```
Furthermore, the unit test suite is now executed for each fresh build. With Jenkins we can build practically every new commit that is merged into **devel**, since there is no licensing contention anymore.

Unfortunately, the Mac OS build is still missing and I want to integrate [CVM-247](https://sft.its.cern.ch/jira/browse/CVM-247), but for a start it works nicely. Thanks a lot Petr!