Remove Provider Account priority attribute
Delete tests for Provider Account priority attribute
prevent 500 on catalog create with non-existing pool

this would lead to a 500 if pool w/ id=13 would not exist:

alias xmlcurl='curl --write-out "\nHTTP code: %{http_code}\n" --header
"Accept: application/xml" --header "Content-Type: application/xml"'

xmlcurl -X POST --user admin:password -k
  http://localhost:3000/api/catalogs --data
    '<catalog><name>haha</name><pool id="13"/></catalog>'

with the patch we get a 422 although the error message is not precise

+ a test for that
cleanup API error handling by introducing fn. render_api_error
Change Provider Selection score ranking

Until this point Provider Selection score ranking was based on Provider Account priority. That's removed, so we change this to a more sane implementation:
- lower score means lower rank
- higher score means higher rank
- nil score means 0 rank
Fix tests after changing Provider Selection score ranking
PoolProviderAccountOption model
PoolProviderAccount controller and views
PoolProviderAccountOption tests
Weighting strategy
Weighting strategy tests
Update Gettext
cleanup shared_examples_for "http.*"
Merge pull request #434 from martinpovolny/api_fix_1

API fixes #1
Merge pull request #432 from ifarkas/provider_account_priority

Refactor Provider Account priority