Add ability to pause build-slaves.

Signed-off-by: Tom Prince <tom.prince@ualberta.net>
Start implementing option to pause a slave.

Signed-off-by: Tom Prince <tom.prince@ualberta.net>
Don't react to "destroy buildbot"
s/not/!=
Check against configurable nickname
- Checked if reason parameter is of type StringParameter.
- Included a check for FixedParameter.
- Added test : test_bad_reason.
Merge branch 'patch-1' of git://github.com/stchris/buildbot
Report errors for all builder at once.

This also changes all of the config error reporting to use `config.error`
instead of sometimes using `.addError`.
Merge pull request #609 from tomprince/builder-errors

Report errors for all builder at once.
Fix a couple of errors introduced by using config.error everywhere.
Lock management: store LockAccess instances in class instances

Moves some common code of converting between Lock and LockAccess to a common
place.
Add some better error handling to 'buildbot try'.

Refs #2392.
- Changed to config.error instead of raising a Validation error.
Remove potentially misleading message about rebuilding builds.

It isn't possible to reliably detect when a build can be rebuilt exactly,
so don't try.

Fixes #2377.
- Fixed test.  And fixed import in forcesched.py.
Wrap looping calls in try-except blocks.

LoopingCall cancels anything after it raises an exception,
so catch them before they reach it.

Refs #1038.
Make contributed pollers use PollingChangeSource.

Refs #1038.
svnpoller: Don't fail when revisions contain changes outside our prefix.

When getting the logs, revisions that don't affect the SVNPoller.svnurl path
are already being filtered out by svn.  Since the poller doesn't even consider
them, I would expect it not to consider unrelated paths that come with the logs
and just filter them out.

Fixes #385.