some formating cleanup
Raaz.Types: New Rounding class added to remove unsafe CryptoCoerce Instances
Raaz.Primitives: Instances for Rounding class added for conversion between BITS & BLOCKS and BYTES & BLOCKS
Raaz.Util.SecureMemory: Instances for Rounding class added for conversion between BYTES & PAGES
rounding class in raaz-hash
rounding class in raaz-cipher
rounding class in raaz-random
rounding class in raaz-core
Merge added the Round class fixes issue #70.
Added hmac and hmac'
Fixed documentation
Changed Typeable constraint to HasName
Fixed bug in HMAC
Tests for hmac
shadowing of hmac function fixed.
add IsString instance for HMACKey.
hmac and hmac' take HMACKey as input

- now that there is IsString instance for HMACKey this should be fine
  for the user
fixed hmac tests.
Merge added hmac and hmac' functions.
x-raaz-core now added to the travis build scripts