Adding a SHA1 hash annotation

Implementing a SHA1 hash descriptor, which represents a hash value that
is computed from the audio file contents. This descriptor is intended to
be used as a unique identifier of a particular audio file for the
further usage as a key in sets, dictionaries, etc.

Relates to #16

- SHA1HashDescriptor was implemented.
- Project name change: HoloProcessors -> Holo.Processing
- Tester class was removed.