Fixes #7538 - Change licensing to MIT license

Due to some requests to loosen the licensing on Hammer, to make it easier to use for other projects, I'd like to suggest change to MIT license. If I understand the process correctly we can do that if all the contributors agree. 

Therefore I'd like to ask the following contributors for ACK or NAK in the comments:
- [ ] @tstrachota 
- [ ] @bgupta 
- [ ] @domcleal 
- [ ] @skottler 
- [ ] @bkearney 
- [ ] @torrancew 
- [ ] @dustint-rh 
- [ ] @komidore64 
- [ ] @adamruzicka 
- [ ] @mmoll 
- [ ] @thomasmckay 
- [ ] @bbuckingham 
- [ ] @iNecas 
- [ ] @eLobato 
- [ ] @lzap 

DO NOT MERGE before the packaging for RPMs and DEBs is finished