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
Merge renaming Cxt to Key.
Removed R.C.Serialize. Fixes #189
bug in capital hex digit checking fixes #191.
Cleaned tests of raaz-cipher by using fromHex
Cleaned benchmarks of raaz-cipher by using fromHex
Removed some spurious inlines and extensions
Merge some test cleanup.