Remove .pyc files from git

.pyc files are probably not needed in git
Use relative path for screenshot in main page

Using an absolute path caused the screenshot to not be visible in
locally published pages.
Add .gitignore files

The .gitignore file in the base directory ignores the __pycache__
directory that is beeing created.
The output/.gitignore file makes it possible to add the output directory
in the git tree and ignore all files in that directory.
git ignore the output directory completely

On second thought, there is no good reason to have the output directory
under git, while being empty all the time.
Remove Download, WIki and Forum from Other resources

The Download, Wiki and Forum are linked at the top of the page anyway.
Add Transifex link in Other resources
Make links in theme relative to present directory

The News link at the top always pointed to www.salixos.org, so there was
no way of previewing the news page locally.
Also, the logos where always loaded from www.salixos.org, now they are
loaded locally.
Load the css from an online location, not locally

The css wouldn't load with a relative URL, so we're loading it from the
server anyway.
Merge pull request #1 from gapan/master

Remove absolute paths, link changes and gitignores