Extend secret expiry / send another secret

[wetoolaguer]

Description

Adds ability to extend expiry of secret https://www.pivotaltracker.com/story/show/166972127

Previously this was the 'resend secret' branch. Since we cannot do it (we don't have access to the decryption key once sent to user), we just added an extend expiry button.

A 'Send Another' option is also added. This copies all the secret's details except the secret itself and redirects to the new form.

Tasks

• [x] Add resend button in dashboard
• [x] Add state for viewed and expired in dashboard
• [x] Handle resending in Controller

The following tasks were added because we cannot do the resend function:

• [x] Add an 'Extend button' - extends the expiry for 1 week
• [x] Add 'Send Another button' - copies secret details(from_email, to_email, etc..) except secret content
• [x] Adds seed for different secret states
• [x] Cleanups Time.now references (Uses Time.current instead)
• [x] Add limit to free users - can extend just once

[wetoolaguer]

@danieldraper added jquery-ujs as well since it's not in the pipeline.