add(server/v1/tests): Port many of the v2 HTTP handler tests to v1

This should cover most aspects of the v1 API but being new to the etcd
code base I cannot promise that or that the tests are even correct.
They do pass though :)
Merge pull request #560 from marineam/test-v1

add(server/v1/tests): Port many of the v2 HTTP handler tests to v1