License should be changed

[4lm]

@henhuy, the license should be changed to MIT, Apache 2.0, BSD-3 etc. AGPLv3+ is IMO not the right license, because it would prevent us to use the code in this repo for contract projects, which often have a period of time in which we are not allowed to publish the source code. The usage of AGPL would force us to instantly publish the source code, which would prevent the possibility of using the code of this repo in contract projects.

@Ludee, maybe you want to share your wisdom on this issue?

PS: GPLv3+ could be a middle ground. Personally, I would just go with MIT, because it's IMO the most flexible one for later use.