Fix Chamber integration

The way that Chamber outputs secure variables now does not require the
`--echo` flag and therefore this can be removed.  This should now allow
Chamber and Overcommit to play nicely together assuming the correct
`includes` paths are set.

I'm going to fix the `includes` paths in a subsequent PR.

Change-Id: I72cfe697310b61c060e71f7da5d04e535790cdfe
Reviewed-on: http://gerrit.causes.com/42488
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Joe Lencioni <joe.lencioni@brigade.com>
Reviewed-by: Shane da Silva <shane.dasilva@brigade.com>
Fix 'include' path for ChamberSecurity

Chamber actually looks in two places by default for its settings files.
The first is `config/settings.yml`.  The second is any `.yml` file under
the `config/settings` directory.  This change makes this the default so
all one has to do is to set the `ChamberSecurity` plugin to `enabled`.

Change-Id: I0087d4649d0140699d72119db391809e22d97c54
Reviewed-on: http://gerrit.causes.com/42489
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Shane da Silva <shane.dasilva@brigade.com>
Reviewed-by: Joe Lencioni <joe.lencioni@brigade.com>