android port

[r10s]

for the record: @cyberta did a a soon, but somehow working android-port using this library: https://github.com/deltachat/AndroidYggmail

we tested that out on a gathering with 20 persons using android devices and https://github.com/deltachat/deltachat-android/ as client, work quite well.

(i am currently on a pr that will make configuration of Delta Chat a bit easier easier, came over this repo to double-check default ports and thought a link to AndroidYggmail makes some sense :)

[r10s]

the mentioned pr that will allow to log in to delta chat by just yggmail-address and password: https://github.com/deltachat/provider-db/pull/199