Remove user from bc-template-keystone

We do not want to allow end users to change this; the only reason to
have this variable is for cross-distro support.
Rename mysql_instance to sql_instance

In preparation to add support for PostgreSQL

Conflicts:
	chef/data_bags/crowbar/bc-template-keystone.json
	chef/data_bags/crowbar/bc-template-keystone.schema
	crowbar.yml
	crowbar_framework/app/models/keystone_service.rb
Switch to generic "database" resource form barclamp_database
Added support for PostgreSQL

Conflicts:
	chef/cookbooks/keystone/recipes/server.rb
	crowbar_framework/app/models/keystone_service.rb
	crowbar_framework/app/views/barclamp/keystone/_edit_attributes.html.haml
Don't execute PG/MySQL specific thing when sqlite is used

plus some fixed typos

Conflicts:
	chef/cookbooks/keystone/recipes/server.rb
Adapt UI and KeystoneService for new database barclamp

Conflicts:
	crowbar_framework/app/models/keystone_service.rb
	crowbar_framework/app/views/barclamp/keystone/_edit_attributes.html.haml
Reworked cookbook to support the merged database barclamp

Conflicts:
	chef/cookbooks/keystone/recipes/server.rb
Don't overwrite sqlite connection string and warn if "sql_engine" is unknown
Disallow SQLite setup

Conflicts:
	crowbar_framework/app/models/keystone_service.rb
	crowbar_framework/app/views/barclamp/keystone/_edit_attributes.html.haml
Don't create a proposal when no "database" proposal exists (bnc#773803)

Conflicts:
	crowbar_framework/app/models/keystone_service.rb
Fix one string to not refer to mysql
Change default database engine to database instead of mysql