added hlint tests to the build matrix.
fixing the matrix.
run hlint right in the begining and skip the rest.
allowed hlint to fail in the build matrix
Merge hlint on travis

This is to improve coding style. Hlint is run on files to check
for better coding standards.
Renamed Cxt and cleaned symmetric and asymmetric primitive classes

* Renamed Cxt to Key
* Removed spurious class members from Auth, Cipher, AuthEncrypt, Sign classes.
Fixed raaz packages with Cxt to Key renaming