Changed platform strings to be x86_64 or i686

Fixes tnc-ba/swidGenerator#10
Merge pull request #10 from tnc-ba/issue10-architecture-string

HW Architecture in SWID tags and softwareIDs
Added setup.py to make the SWID generator easily installable

The swid_generator script can now be installed to your local PYTHONPATH
with ::

    python setup.py install

To install only symlinks to the sourcefiles (which means that code
changes are immediately reflected in the installation), use ::

    pip install -e .

Refs tnc-ba/strongTNC#40.
Update README.rst

Removed wrong indent
Changed to use rpm instead of yum

Fixes tnc-ba/strongTNC/issues/108

Removed debug print

Removed dependency section from Readme

Renamed environment from yum to rpm
Updated README changed yum to rpm
Changed --environment option to be rpm
Introduced visitor for output generation

Added visitor to print output, no caching in list anymore

Moved document_separator to visitor

Cleaned up comments

Removed debug print

Style fixes + print function

- Imported print function
- Removed unnecessary parens from from if
- Removed unused import

Added file encoding header
Changed identation of pretty output from tab to two spaces

Fixes https://github.com/tnc-ba/swidGenerator/issues/14
Removed extra newline from software-id mode

Fixes https://github.com/tnc-ba/swidGenerator/issues/15
Removed visitor pattern and introduced generators

- Introducing generators allows lazy generation of software-ids and SWID
tags
- Removed print visitor. Output printing is now done with a print function which takes the generator

Added docstring to create_swid_tags method

Changed to use relative imports

Removed obvious keyword from create_swid_tags and create_software_ids

Moved closing parenthesis to previous line

Removed unneeded parentheses

Changed docstring for create_swid_tags

Removed unused parameter
Switched license to MIT

- Updated information in setup.py
- Added LICENSE.txt
- Added license information to `swid_generator/main.py` and `README.rst`

Fixes tnc-ba/strongTNC#97.
Added .coveragerc
Fixed name of program in usage output
Abstracted away generator printing

Refs tnc-ba/strongTNC#110.
Renamed swidgenerator_argumentparser module

The module `swidgenerator_argumentparser` is now simply called
`argparser`. The context is obvious at import time due to the relative
import.
Removed double newline special case
Converted OutputGenerator methods to module level functions
Optimized full SWID generation

Previously, when obtaining the list of all files per package, it was
all done in the beginning, before generating all the XML tags. Now the
files per package are fetched just before creating the XML tag, thus
speeding up the time until XML tags are outputted.
Added mocking of yum to tests