added module capturing memory abstraction
pageSize Parameter added.
Secure memory abstraction implemented.
CryptoCell with Secure Memory and CryptoArray
Gadget class added
raaz-hash-sha fixed for the gadget implementation.
MAC removed
Merging memories and gadget

Implements.

 * Memeory: an abstraction on memory elements that can also be
   allocated locked.

 * Gadgets: These replaces the Implementation classes. The advantages
   are

    1. A unified interface for all crypto primitives, hash, mac etc

    2. Stateful i.e. the internal states are now implemented as
       memories.  By initialising the gadget with locked memory
       element one can make sure that critical data are not swapped
       out.