store last message received date in conversation
very basic mam support
added max history age (default 1w). automatically sort newly added mam messages
save server id from mam messages. check for dups before adding mam
changed lastMessageReceived into lastMessageTransmitted to account for sent messages as well. (will trigger on sm ack)
mark otr messages as no-store for mam
various mam improvments
refactored phone contacts merger
Merge branch 'feature/mam' into development

Conflicts:
	src/main/java/eu/siacs/conversations/services/XmppConnectionService.java
reverse through mam history when loading larger chuncks