Crud manifests

I have few things to say regarding this PR and few TODO stuff.

1) Consider using virtual-env with system-site-packages option and install locally modules in virtual-env  using pip via ( pip install -I <module-name>)
a) virtualenv --system-site-packages robottelo
b) and install locally modules in virtual-env  using pip via (pip install -I boto)
2) I have updated the requirements.txt file with the necessary requirements to use the stageportal module.
3) We would also require python-rhsm, m2crypto, openssl-devel, rpm-python distribution packages to progress here.
4) Though stageportal module inturn calls python-rhsm module it is still required because of the certs which can be easily found from the distribution packages.
5) I decided to use m2crypto that of the distribution package, if needed one could install it in virtual-env using pip with the below workaround
a)  pip install m2crypto --no-clean
b) cd /venv/build/M2Crypto
c) chmod u+x fedora_setup.sh
  ./fedora_setup.sh build
  ./fedora_setup.sh install
6) While installing modules with pip, you may need to install "Development Tools", I decided to install that group 
as I was constantly being asked for few devel-packages 


1) Currently I have added this feature to tests/common/manifests.py, me  thinking is this the right place for it to go? 
2) TODO fix some PEP8 line length issues 
3) TODO Need to add logger for the else part at few places

Tested interactively and it did work. :)

Suggestions please :)