Add HTTP Nowhere toggle method

Also reformats a large chunk of the global toggle code because
otherwise my text editor couldn't detect whether braces were properly
matched (???)
Add toolbar button for HTTP Nowhere
Disable HTTP Nowhere menu item when HTTPS Everywhere is disabled
Don't reload from the cache
Add HTTP Nowhere icons
Tweak HTTP Nowhere label wording
Revert "Disable HTTP Nowhere menu item when HTTPS Everywhere is disabled"

This reverts commit bda2202847abd0e7a71febd566b74509644eeed3.
Rewrite HTTP Nowhere using http-on-modify-request
Merge branch 'master' into http-nowhere

Conflicts:
	src/components/https-everywhere.js
Delete old HTTP Nowhere proxy prefs
Merge branch 'master' into http-nowhere
Revert "Revert "Disable HTTP Nowhere menu item when HTTPS Everywhere is disabled""

This reverts commit 27119a135747d6983e7da8ab1942e23fbeecad53.
Hide irrelevant menu items when HTTPS-E is disabled
Explicity pass httpNowhereEnabled arg to replaceChannel
Merge pull request #379 from EFForg/http-nowhere

Add toggle mode for HTTP Nowhere