Add basic KV REST html UI and embedfile tool

This change adds a basic UI for querying the REST API from a web GUI at /kv/rest/.
It avoids the external dependency of another file (rest_ui.html) by generating a
file through the go generate command and the embedfile tool before compilation.

This is all a preamble to a better REST API, but also autogenerated documentation
using embedfile and go generate.
more appropriate naming
use local checkout path for embedfile
use go install instead of go get
fix Docker build

the problem was that ./bootstrap.sh is not actually run for the Docker builds;
the devbase image is created in ./build/devbase and cannot access anything
outside of that directory.

It would be better to move embedfile out of ./tools into, say, build/devbase/tools,
in which case we could install it in godeps.sh instead
no more embedding. Move to AngularJS
Merge branch 'andybons/restui' of github.com:cockroachdb/cockroach into andybons/restui
remove embedfile stuff
remove original rest UI file
rename to rest explorer. add todo
adjust Dockerfiles
Merge pull request #224 from cockroachdb/andybons/restui

Add basic KV REST html UI