Introduced a config file to store test parameters

1. Removed shell script to store environment variables
2. Introduced a config file to store test parameters
3. Introduced an option to store host, user in config file so the user can just run #fab <taskname>
4. Moved all test paramters to the new config file
Merge pull request #5 from sthirugn/testupdate

Introduced a config file to store test parameters
Fiddle with readme

From top to bottom:

1. Drop the leading `===`. It is interpreted as an `<hl>`.
2. Wrap the ordered list at 80 chars.
3. Fix all fenced code blocks. Fenced code blocks (denoted by triple-backticks)
   do not require any tabbing beyond that which denotes which block they belong
   in, so place fences in apparently correct locations. The hash mark is a
   convention that indicates a command needs to be run as root, and it appears
   to be unnecessary in most or all cases, so drop it.
4. Use single backticks to denote inline code. Using triple backticks for inline
   code is syntactically incorrect.
5. Make paragraphs flow together. Do not place "Note:" on a line all by itself,
   as it is not a paragraph.
6. Add a blank line after the "code contribution" header, for the sake of
   consistency and niceness.

Also, fiddle with the wording throughout the readme.