Fixing is_imported flag to indicate upstream translations

Basically:

• is_current -> is_current_in_ubuntu

• is_imported -> is_current_upstream

Implementation

• (Done) 544420 Rename is_current/is_imported flags to is_current_ubuntu/is_current_upstream (cleanup)

• 564477 Provide isCurrent and makeCurrent methods to hide distinction when needed (convenience)

• (Done) 545100 Rename is_published to from_upstream on TranslationImportQueue (cleanup)

• (Done) 545123 Change 'changed in Launchpad' terminology to be 'changed in Ubuntu'

• (Done) 545365 Remove reference to 'published' uploads from the UI (cleanup)

• (Done) 545070 Change terminology in ExistingPOFileInDatabase (cleanup)

• updateTranslation cleanup and changes
  • Find exact same translationmessage
  • Privilege checks for updateTranslation replacement calls

  • (Done) 546334 Sanitization and validation code into utility

  • 546521 submitSuggestion method

  • 562858 Clearing/unsetting translations

  • (Implemented) Dismiss suggestions

  • setCurrentTranslation

  • Diverge translation
  • Replace updateTranslation calls with calls to new methods

• 546310 Adapt UI to work with new flags and new semantics for upstream projects

• Translations overview pages for projects (statistics update)

• POFile:+translate filters

• Privileges for updateTranslation
• Migration script: set is_current_upstream from is_current_ubuntu flag on upstream projects, clear is_current_ubuntu if there is no link
• Update message-sharing-merge script for the new semantics
• Fix up gettext-check-messages script to be symmetric for is_current_upstream and is_current_ubuntu flags

• 545354 Enable sharing between templates in products and Ubuntu