Remove useless CSS rules.
Fix a syntax issue.
Rephrase icons and relative URLs.
Remove 'backgroundservice' permission.
Typo
Make version number a completly arbitrary string.
Reduce some confusion regarding application's origin.
Merge branch 'master' into runtime-security
Merge pull request #38 from mounirlamouri/runtime-security

Various small changes in runtime-and-security model proposal from Mozilla.