fix execution of git merge-base and remove extraneous newlines

commands.getoutput was producing an error message "'{' is not recognized as an internal or external command," I assume it was trying to run the command in a subshell using sh syntax, which is not valid in a cmd.exe shell.

The whole script should probably be converted to 'subprocess'

Also `if baserev != oldrev:` was failing due to the newline printed after the revision number by the command 'git merge-base'.
Show the builder description in the builder's web status page.
 - add builder's description in the DB
 - update builder.tpl.jade
Fix typo
 - Add migration unittest: test.unit.test_db_migrate_versions_039_add_builder_description
resultspec: treats None as smaller to anything

This avoids useless 500 when the data set contains
null datetimes
test for null datetime sorting
Refresh the First-run instructions.

- Move to pip
- Don't activate the virtualenv (IMO not necessary)
- Put less emphasis on docker.
- Remove the use of tail
- Refresh the logs (2011 and 2009 !)
- Explain a bit more what the commands are for.
more tests for resultsspec's nonecmp

Signed-off-by: Pierre Tardy <pierre.tardy@intel.com>
Merge pull request #1313 from tardyp/t2978

Fix: Loading the waterfall while a build is in progress return 500

Fixes ticket:2978
Update after review from Dustin.

- One sentence per line
- Restored the ``code-block``s
- language fix
Actually create two virtualenvs
Implement a real pager on the build page
Don\'t put a <a> in the pagination if not needed
Bug 2986: add tests for migration 037
drop columns in a way that works on all supported DBs

Fixes #2986.
Merge pull request #1314 from benallard/patch-3

Refresh the First-run instructions
 - pep8/pylint fix
 - make sure the new description col is null
Merge pull request #1315 from benallard/t2975

Implement a real pager on the build page
Fix docs for IRC status to specify correct plugin path
Merge djmitche/buildbot:irc-docs-fix (PR #1317)