Fixed the last data transfer session unit test.

Created a linked mock remote file and remote NS access to allow proper environment in unit test involving migrations.
Added missing file.

Creates a linked mock remote file and remote NS access to allow proper environment in unit test involving migrations.
Fixed using pointer to job after passing it to the reporter by copying the necessary data at creation of the tape write task.

Fixed confusion between archive and retieve in logging "path" and creation of file object by file factory.

Refactored the Mocks to eliminate code duplication. (for Mock{Archive|Retrieve}{Job}Mount}

Fixed mount criteria computation.

Removed mocking of classes where functions have non-copyable argumentes (unique_ptr).
Replaced NULL references to watchdogs to dummies where necessary.

Fixed 1 last bug that was preventing DataTransferSessionGooddayRecall test to succeed. It now succeeds.

Fixed 4 bugs that are preventing DataTransferSessionGooddayRecall test to succeed. One more left: next commit will do

Completed support for tape density and add usage of at() in a vector access to prevent segfault in unit test.
Removed some throw() specifications which led to segfaults.

Removed requirement that the initial root entry should be unowned as mock over normal file system cannot achieve this.

Simplified redundant code in symetric function for ArchiveMount.

Adjusted unit test to accomodate the new structure (SchedulerDatabase::RetrieveMount is now a pure virtual class).