renaming cellLoad to cellPeek, fixes #176
renaming cellStore to cellPoke, fixes #176
Merge rename cellLoad/cellStore to cellPeek/cellPoke fixes #176

- This better reflects the naming because we are mainly concerned with
  Storable types and not EndianStore types.
cabal file added for haskell platform 2012.4.0.0
moving PARALLEL_BUILDS option to global for all builds
GHC_VERSION added to the build matrix where HASKELL_PLATFORM is given
commands to prepare the system, such as to install ghc & cabal as per environment variables
command to compile travis build script
new install section of travis YAML for installing dependencies and then raaz packages
new before_script section of travis YAML for configuring and building raaz packages
new script section of travis YAML to run test suites of raaz packages
added a few more sections to travis YAML to make tarball of packages and output final build messages
haskell script to be used to install, build and test raaz packages by travis
added fast_finish option to Tavis YAML
added a few comments to Travis YAML
new TravisEnv type added with some cleanup
refactoring of build code alongwith using TravisEnv type
new helper functions addded for type TravisEnv
refactoring and fixup of some functions
using getEnvironment instead of lookupEnv (base >= 4.6.0.0)