[Sessions] First session is now started on first track

Signed-off-by: Miguel M. Almeida <miguelcma@gmail.com>
[LPackage] fix an eventual bad access while getting a value

Signed-off-by: Miguel M. Almeida <miguelcma@gmail.com>
[Demo] change user identify method on demo app

Signed-off-by: Miguel M. Almeida <miguelcma@gmail.com>
[CodeReview] Fix an error on copyright headers

Signed-off-by: Miguel M. Almeida <miguelcma@gmail.com>
[Demo] use default identifyUser: on demo app

instead of using `identifyUser:alias:`

Signed-off-by: Miguel M. Almeida <miguelcma@gmail.com>
[Dates] Use "Unique Now" on all dates of Liquid

All `[NSDate now]` are now incremented in one millisecond, to ensure that there
are not two event at the same instant. So, an order is always guaranteed.

Signed-off-by: Miguel M. Almeida <miguelcma@gmail.com>
[Device] Remove _uid from device

Signed-off-by: Miguel M. Almeida <miguelcma@gmail.com>
[User] Fix issue while saving user to disk on identify

Signed-off-by: Miguel M. Almeida <miguelcma@gmail.com>
[Tests] Small improvements on Kiwi tests

Signed-off-by: Miguel M. Almeida <miguelcma@gmail.com>
[Session] Avoid two _startSession events when app is started

Signed-off-by: Miguel M. Almeida <miguelcma@gmail.com>
[Queue] App in foreground not recovering http queue from disk + Tests

Signed-off-by: Miguel M. Almeida <miguelcma@gmail.com>
[Reidentify] Change reidentify endpoint

Endpoint changed from

`/collect/users/:user_id/:device_id/reidentify`

to

`/collect/users/:user_id/alias`

Signed-off-by: Miguel M. Almeida <miguelcma@gmail.com>