[DOC,FIX] Fixing HTTPS link to trac in dox/pages/index.dox.
[DOC] Fixing embedded image in Gaps documentation.
Merge pull request #72 from holtgrewe/fix/doc_https_link

[DOC,FIX] Small documentation fixes.
[DOC] Updating README.mason_variator.
Merge branch 'develop' of git://github.com/seqan/seqan into develop