etcdhttp: non-blocking sender
scripts: add build, cover and update test

This adds a build script that attempts to be as user friendly as
possible: if they have already set $GOPATH and/or $GOBIN, use those
environment variables. If not, create a gopath for them in this
directory. This should facilitate both `go get` and `git clone` usage.

The `test` script is updated, and the new `cover` script facilitates
easy coverage generation for the repo's constituent packages by setting
the PKG environment variable.
scripts: remove non-functional Dockerfile
Merge pull request #1027 from jonboulle/master

raft: remove unused alwaysreadyc
Merge pull request #1001 from coreos/sender

etcdhttp: non-blocking sender
*: fix a few small issues identified by go vet
Merge pull request #1030 from jonboulle/assorted

*: fix a few small issues identified by go vet
Merge pull request #1028 from jonboulle/build

scripts: add build, cover and update test
store: convert Watch to interface
etcdserver: add waitForEvent and encodeResponse coverage
etcdserver: add test coverage for parseRequest
api: address review comments
etcdserver: split out functional test to new package
etcdserver: remove superfluous context
Merge pull request #1017 from jonboulle/api_tests

HTTP API test coverage, pt 1
Merge pull request #1029 from jonboulle/docker

scripts: remove non-functional Dockerfile