Renamed CTA/tapeserver/castor to CTA/tapeserver/castor_checkout in preparation for the moving the sub-directory CTA/tapeserver/castor/castor up the directory tree

Added a check for fresh block cleanliness in getFreeBlock (for both DataFifo in migrations and RecallMemoryManager).

Moved MemException from castor::tape::tapeserver::daemon to castor::tape::exceptions and changed the uses in the code
The tapeserver/daemon/Exception.hpp was empty after that, he has been removed

Move to a static member function of payload and renamed it zeroAdler32

Excute is now simpler, some dead code has been removed, so does Payload::EndOfFile, which is now castor::tape::exceptions::EndOfFile

The new functionnality allows reading of tape blocks into the MemBlock. The size
of the tape blocks is managed here.

 thus if m_failled is set at true, then the block is not usable

MemBlock, MemManager, MemManagerClient, MigrationJob,
TapeReadFileTask, TapeReadTask, TapeSingleThreadInterface,
TapeReadSingleThread, TapeWriteTask, TaskInjector
into castor::tape::tapeserver::daemon

Indeed, there was a clash into auto_ptr destructor (which does a delete) and the allocation which was done using new[]

Fixed inheritance from std::exception (const correctness of what()). This required declaring m_what mutable.
Created a multithreaded unit test.
Created an automatic exception thrower for unhandled errors.
Ported from previous proof of concept the threading primitves and made them production level (with error checking).
Added unit tests for threading primitives.

Lowercased/Upercased some namespace/class names for homogeneity.

Implementing correct usage of exceptions. This means that the serrno is correctly set in the C interface now. The correct way to display an error message now is thus to first use sstrerror and then use getErrorMessage for a complement of information