archive search - implement proprietary period limits

[VincentMcIntyre]

Data taken recently (within the "proprietary period") must not be made available to users outside the observing team for those observations.

The search code needs to implement:

• no anonymous access to any data within the proprietary period
• no access for authenticated users who are not (according to OPAL) listed on the proposal for the project number embedded in the data files

[VincentMcIntyre]

NB: any data retrieval code modules may need to perform this check, independently.

[MatthewWhiting]

Implemented for anonymous queries.

As OPAL authentication not enabled yet, all "ATNF" users in the database (most people involved in development) are able to see all data.

[DavidSmith]

implemented, proprietary period is 18 months for anonymous login, and access within that granted if the user has logged in with opal id and that id is associated with those projects.