Allow arbitrary requests to be performed via SocialNetwork

This allows clients to perform some request to, for example, retrieve
the identifier of some graph object that they wish to set as the node
in the model, without going through multiple request round trips.
Merge pull request #87 from chriadam/master

Add arbitrary request API to SocialNetwork adapter
[Email] - Add lastUpdatedAccountTime() binding.
Merge pull request #90 from VDVsx/master

[Email] - Add lastUpdatedAccountTime() binding.
Merge pull request #88 from adenexter/contacts-fixes

Assorted fixes for nemo contacts plugin
Ensure time is updated when WallClock is enabled
Merge pull request #91 from martinjones/master

Ensure time is updated when WallClock is enabled
Add types which provide asynchronous import/export of vcards.
Match filter against more properties than display name.
Update the SeasidePerson test to allow for caching of display label.

Also fixes a longer standing mismatch in logic between the test and
SeasidePerson about when the contactChanged() signal is emitted, by
favoring SeasidePerson's interpretation.