Deploy recaptcha support for https distribution strategy

From org/sponsors/SponsorF/Year2: "13. bridgedb: Deploy recaptcha support for https distribution strategy. Right now our bridgedb service is getting bombarded by automated bridge requests, which look an awful lot like an adversary trying to enumerate all the bridges. If we stick a manual captcha step in, we force them to move forward at the arms race."

From talking to Aaron in December:

1. We have recaptcha support merged into BridgeDB, but it is currently not enabled. (legacy/trac#1836 (moved))

2. Two subtasks of this deliverable should be "Move bridges.tp.o to a Tor VM" and "Get aagbsn access to bridges.tp.o." (legacy/trac#2301 (moved))

3. There is some question as to how Google will react to the recaptcha implementation. We should talk to Google people before enabling it. Aaron is going to talk to them, possibly after an introduction by Mike or Jake.

AFAIK, 2 is in progress and 3 and 1 have not been started.

Can we agree on some schedule when these substeps and the overall deliverable are expected to be done?

Optimistically assigning to the July milestone.