Merge branch 'release/0.1'
support multiple rel values for one hotkey
unregister hotkeys on unload
add icons on urlbar
button collapsed on creation
remove buttons on unload
readme
<^>
Support rel=top

readthedocs uses it

cf: http://microformats.org/wiki/existing-rel-values#dropped
Remove duplicated stuff on hook_func
do not unload during shutdown

there is no `window` object thus error occurs.

cf:
https://addons.mozilla.org/en-US/developers/docs/sdk/latest/dev-guide/tutorials/load-and-unload.html
readme
support rel=up/start
Hook on pageshow

Now it responses on back/forward event.

-   Works on Firefox Nightly 24.0a1 (2013-05-25).
-   Requires latest sdk:
    git tag 'firefox-24-05-24-2013', revision 0073b03
Version 0.2

Works better
Merge branch 'release/0.2'

Conflicts:
	package.json