Add a deploy schemas command

[dmcassel]

Roxy can create a schemas database and associate it with the content database, but there's no explicit way to upload schemas. Add an "ml {env} deploy schemas" command.

Workaround:

• Use "ml recordloader" with a config file that targets the schemas database (wiki).
• Add a command in app_specific.rb

[dmcassel]

The command will deploy schemas to the Schemas database if no app-specific schemas database is defined. It prints a warning when it does that, since clean and wipe won't remove those schemas.