update README.md
Merge branch 'master' of github.com:SSilence/selfoss
Fixes SSilence/selfoss#386
Merge pull request #387 from Weishaupt/master

Fix for #386
new spanish translation (thanks a lot to Matias Perrone)
new spanish translation (thanks a lot to Matias Perrone)
Merge branch 'master' of github.com:SSilence/selfoss
Merge remote-tracking branch 'upstream/master' into subscribe
clean up 'register' button, only appear when browser is firefox