fix for issue #240 (srx-branch cluster fact gather)

fix for jnpr.junos.utils.config.Config.load() ... when:
   configuration results in an rpc-error that does not contain
   any error-severity='error'; rather contains 'warning'.
Merge pull request #246 from vnitinv/unit-tests

Unit tests, code coverage at 99.97%, 3 lines remaining.
Unit test cleanup, plus 1 more line!
Merge pull request #247 from shermdog/unit-tests

Unit test cleanup, plus 1 more line!
updates to fix facts
fix fact gather order
Merge pull request #249 from Juniper/unit-tests

Unit tests up to 100%
Merge remote-tracking branch 'juniper/master'
Merge pull request #250 from jeremyschulman/master

bug fixes relating to fact gather
Added new status badges
Update README.md
Merge pull request #252 from shermdog/badges

Added new Status Badges
Update setup.py
to support VMX
Merge pull request #257 from vnitinv/master

to support VMX
fixes issue #256 - relating to using the "replace" marker
set default load action to replace.  add :merge: option to disengage replace
Merge remote-tracking branch 'juniper/master'
Merge pull request #259 from jeremyschulman/master

fix #256 - activate 'replace' option as default with config.load()
enhancements for fix#256