Add license expiration date and logic

[konstjar]

Currently license is assigned to user without any expiration while licenses have expiration date in some institutions. Thus we need to add:

• expiration date in DB
• expiration date in request (optional)
• logic to disable vocabs access after expiration date
• logic to update license expiration date

[mik-ohdsi]

• As an Athena user I want to request access to a license protected vocabulary with providing the expiration date of my current license so that the availability for download is duly restricted according to my subscription.
• As an Athena user maintenance administrator I want to be able to enter an expiration date with every license request while the default date for this field is the 31st December 2099 so that I can process license requests accordingly.
• As an Athena DB administrator I want to have a function that limits download and access to license restricted vocabularies according to system date and expiration date of the license so that the Athena GUI can show this to the end user accordingly.
• As an Athena user I want to see my expiration date for license restricted vocabularies that I was granted access to so that I am not surprised by restriction of access and can update my license in a timely fashion.
• As an Athena user I want to be able to create an update request of an existing access to a restricted vocabulary by clicking a button in the download area so that I can extend my access according to my subscription (including providing proof of my updated subscription).

optional improvement of the license process:
As an Athena user I want to provide proof of my subscription (e.g. by file upload) to license restricted content along with the request for access so that the process for granting access can be simplified and expedited.

Very optional improvement of the license process:
As an Athena user I want to be able to go through a 3rd party API to provide proof of my subscription by logging in to the 3rd party (like PayPal) and have the respective API confirm the valid subscription date with my 3rd party user name so that I can get access to the restricted content in a self-service process.

Addition to the download page:
As an Athena user I want to be able to get access to otherwise free content that requires passing through an End User License Agreement / Acknowledgement page by viewing and confirming this 3rd party agreement (either accessible through URL or saved as a copy in Athena) so that legal requirements before download of 3rd party content can be satisfied.