Added raven and raven-vue plugin, updated gon_helper with data needed for...

Added raven and raven-vue plugin, updated gon_helper with data needed for raven and created raven_config, required by application.js

Added is_production to define sentry environment

Removed as much jQuery as possible

Added public_sentry_dsn application_settings helper method

Use URI module instead of regex for public dsn

Removed raven-vue and load raven on if sentry is enabled

Add load_script spec

added raven_config spec

added class_spec_helper and tests

added sentry_helper spec

added feature spec