Change project licence for one recognized by OSI

[virgile-dev]

Is your feature request related to a problem? Please describe.
Currently the uMap licence is WTFPL.
While applying to grants (ex : NLNet NGI's) we found that not having a licence recognized by the OSI could be a blocker.
Describe the solution you'd like
How about changing to AGPLv3 which is widely used as a strong copyleft licence.

Describe alternatives you've considered
We could ask the OSI to recognize the WTFPL. They have a process on their website.
Though I'm concerned it won't do as WTFPL might a bit too minimalistic for them ^^

Additional context
Google grants and contribution programs also require a licence from OSI.

[almet]

Because the license is WTFPL, we can probably change the license to whatever we want.

+1 for whatever works for you (AGPLv3 would be great)

[davidbgk]

Done in #1605