implemented new share structure

Implemented a new improved share structure.
The layout of the custom-serialization is desecribed in
"serialized.txt".
Also added some unit-tests to verify the functionality of the new
classes.
everything now working with new shares

Everything (the SecrethSharing schemes) and the test-cases are now
compatible with the new shares.
added documentation to RabinBenOrShare
Merge pull request #10 from efrantar-tgm/shares

New Share Structure

NOTE: I'm not too sure about the information checking changes, but will refactor the code anyway later on