Add imports API.

Fixes issue #123
Remove indigo dependency.

To reduce the amount of code that I support, I am taking indigo private.
Replace indigo with the net/http package and tango. Tango is a subset of
indigo converted to work with net/http.
Complete package badge implementation.
a badge for GoDoc :heart:
Merge pull request #131 from nathany/badge_self

a badge for GoDoc
Fix the bookmarklet.

The bookmarklet was broken on the transition from indigo to net/http.
Improve tools page.

Add tools page support for directory and command pages.

If a package is missing a package declaration comment, then add
a blurb about how to add the comment and why it's important.
Pull tango into gddo as httputil
Move badge from https to http.
Change copyright and license.
Replace httputil router with net/http ServeMux
Remove reference to old license.
Revert 59a8b306c3340ce508cb5c2d5805ad99431bcce4
Define constants for frequently used MIME types.
Remove unused fields and consts.
Merge remote-tracking branch 'mipearson/sidebar' into sidebar
Add command line flag to enable sidebar.

The sidebar is not ready for production.
Update README.markdown
database: add option to hide doc from search.
Add API section.

Very rough attempt, just to get this started.