Authenticate user for vocabulary bundle download

[acumarav]

download vocabulary bundle calls should be authenticated add limits for downloads add licenses check before download

[mik-ohdsi]

just a comment here: I think the first requirement is harder to solve than the other two.

1. authentication - once a download of a zipped bundle is initiated (click on link), another authentication step is required for the athena user who requrested that download bundle (e.g. enter only password for that user)
2. limits for downloads - we have noticed that sometimes download bundles are requested multiple times, as if that link was shared with many people, generating considerable traffic on Athena. We propose that counts are observed and that after counts have exceeded a certain threshold (20 downloads?) the bundle download is blocked, generating an error message (e.g. "you have exceeded your download quota of 20 downloads for this bundle")
3. if in the bundle there is licensed content, immediately before download, the user's license validity is checked again and an error pointing at the vocabulary in question is returned. this also relates to issue #224 .