MediaManager: picture downloading is handled now by media manager
Settings: handle correctly user's picture
Update prev_content type (defined as NSDictionary* now)
BugFix: handle correctly kick/ban/unban user from chat room
- Handle IRC style commands (/kick,/ban,/nick...) in room.
Note: /join alias and user power level commands are not supported yet.

- Switch from the deprecated msg.content.prev to msg.prev_content.
memberName: return user_id as fallback
Fixed [MXSession members] array result.
Improved invite tests
Fixed [MXSession members] array result.
Improved invite tests
Join correctly the privite rooms at which the user is invited.
Prepare power level display in room members list
Room Details: fix layout of room members list
Add powerLevels property to retrieve the current power level of room members
Room details: Handle power levels of room members.
Display unsupported/unexpected messages in room details with red color
Bug Fix: Handle correctly room members list
Room details: Shade invited users
Add new App settings: notifications, all events. Disabled by default (not implemented yet).
Room details: display all events if this is requested by the application user.
Room details: highlight incoming messages including username or user's display name (+ Handle user's display name change).
Handle new events notification