validate/prevent alerts from being created on front end side

[dollschasingmen]

otherwise deal with errors like:

ActiveRecord::RecordInvalid: Validation failed: Email can't be blank

• 17 non-project frames
  18
  File "/usr/local/bundle/gems/aleph_analytics-0.1.0/app/controllers/alerts_controller.rb" line 35 in block (2 levels) in update
• 2 non-project frames
  21
  File "/usr/local/bundle/gems/aleph_analytics-0.1.0/app/controllers/alerts_controller.rb" line 33 in update

• 80 non-project frames
  22
  File "/usr/local/bundle/gems/actionpack-4.2.4/lib/action_controller/metal/implicit_render.rb" line 4 in send_action
  23
  File "/usr/local/bundle/gems/actionpack-4.2.4/lib/abstract_controller/base.rb" line 198 in process_action
  24
  File "/usr/local/bundle/gems/actionpack-4.2.4/lib/action_controller/metal/rendering.rb" line 10 in process_action
  25
  File "/usr/local/bundle/gems/actionpack-4.2.4/lib/abstract_controller/callbacks.rb" line 20 in block in process_action
  26
  File "/usr/local/bundle/gems/activesupport-4.2.4/lib/active_support/callbacks.rb" line 117 in call