VCS-74: Add +build tags to tests, to allow selectively running suites for different VCSs

[m0j0hn]

As a developer, I would like to be able to selectively run tests, so I do not test code I did not modify.

As a developer, I would like to be able to selectively run tests, so I do not need to install tools I do not normally use (BZR, SVN, et al) just so I can get tests to pass when testing locally.

AC: "+build" tags added to *_test.go files, and CI config files to test all by default.

[dmitshur]

This has the tradeoff that running go test will no longer run all tests, is that right?

[m0j0hn]

yes, that is correct -
this SO article is my reference on this: http://stackoverflow.com/questions/24030059/skip-some-tests-with-go-test
I'm not totally happy that it "does nothing by default", but the alternative seems to be adding "!nameX" to every "*_test.go" that is not "nameX_test.go", which gets really bad when adding new "nameX" modules, for new values X - if that makes sense.

[m0j0hn]

@mattfarina @technosophos Can you please consider this Issue and the PR for its fix?
#75