Speed up finding of default_platform

Rather than listing all nodes, simply search
for the admin node.
Remove node.save during webui list operations

listing of all nodes or unallocated nodes caused node.save
operations on all nodes, which can cause races.
Add travis.yml

Create config file for travis CI.
Merge pull request #1049 from bkutil/travis

Travis
Stub out proposal save in crowbar controller tests
Ensure @@CloudDomain is reset before the tests as well
Fix case when role_constraints is not defined for a role passed
Merge pull request #1050 from vuntz/merge-roxy

apache2: Fix the status.conf template for SUSE
Drop the index test for now, there is no easy way to test
Merge pull request #1047 from dirkmueller/default_platform

Default platform
Node target_platform fallbacks to default_platform

The default platform of the nodes is inferred from the platform of the
admin node (and is empty if there's no admin node - possible bug?)

Move the default_platform helper code to NodeObject class, where it gets
cached.

Then use it in the target_platform as a fallback.
Merge pull request #1052 from bkutil/fix_default_platform

Node target_platform fallbacks to default_platform
Merge pull request #1051 from bkutil/test_fixes

[WIP] Fixing tests so we're green in travis
Travis CI should build only master
Add build status badge
Merge pull request #1053 from bkutil/fix_travis_yaml

Fix travis yaml
Do not re-query for proposal objects

The first collection of proposal objects seems to be read-only (i.e. no
destructive ops are performed on it, so there should be no need
to do another query.

This cuts loading the barclamp index page down by almost 50% (1500ms -> 800ms
on a warmed-up server).
Move role revision updates to a separate method
Use proper locking for node allocation

save is refactored to accept a code block that needs to be
protected with the role lock. Make use of that in allocate
and convert usages of previous allocate functions accordingly.
Merge pull request #1055 from bkutil/remove_duplicate_query

Do not re-query for proposal objects