Updated install.txt

You have to install python-dev to compile PIL and reportlab.
Thx to JayRob for the hint.
Merge pull request #82 from ostcar/stable/1.3.x

fixed changing language on the projector
Prepared 1.3.1 release.
Updated django from 1.4.2 to 1.4.3 in requirements.txt
Set version to 1.3.2 (unreleased)