Image-sig is dead [ci skip]

Image-sig is dead, long live GitHub & IRC
Image-sig is dead [ci skip]

Image-sig is dead, long live GitHub & IRC
Image-sig is dead [ci skip]

Image-sig is dead, long live GitHub & IRC. Also cleanup HTML.
Clean up

Move old dists download instructions to installation instructions.
Clean up ; wording [ci skip]
No need to send empty PyPy coverage to Coveralls

Otherwise it just shows up as grey, question mark:
https://coveralls.io/builds/929022
Change hyperlinks to rst format [CI skip]
Change hyperlinks to rst format [CI skip]
Merge pull request #768 from hugovk/bomb_warning

Change hyperlinks to rst format [CI skip]
Wording [ci skip]
Wording [ci skip]
Factor and move note
We now provide OS X binaries ; clean up