small refactor in models/deployment
destroy --> destroy! to force exception
add test for instance.launch!
API deployables: implement delete
specs: request spec for deployables API #delete
API Entrypoint: add Deployables
API: Make time helpers more defensive

Check for nils, convert datetime parameter to the true datetime (to prevent
errors when using ActiveSupport::TimeWithZone on Ruby 1.8 [1]).

[1] https://github.com/aeolusproject/conductor/pull/273#issuecomment-11516852
deployables api: raise exception when delete fails
spec: add test for deployables in API entrypoint
routes: add API deployables destroy
spec: deployables api, when delete fails expect 500
Merge pull request #274 from jistr/harden_api_time_helpers

API: Make time helpers more defensive
fix cost formating in deployment and instance properties
Cucumber scenarios for delete of Provider Type API

https://redmine.aeolusproject.org/redmine/issues/3935

Added scenarios and step definitions for Provider Type API - show action
Rspec for delete action of Provider Types API

https://www.aeolusproject.org/redmine/issues/3936
Added delete action for Provider Types API

https://redmine.aeolusproject.org/redmine/issues/3937

This adds new permissions for modifying of Provider Type for global admin.
Both db/seeds.rb and lib/tasks/dc_tasks.rake (dc:upgrade task) modified.
Merge pull request #283 from petrblaho/provider-types-api-delete-rm3884-3

ProviderType API - delete action - 2. revision
Merge pull request #281 from hacxman/deployables_entrypoint

API Entrypoint: add Deployables - 2
Merge pull request #278 from hacxman/deployables_delete-rebase-2

Deployables #delete action
API deployables: XML view for #show