Update README.md

This is part of issue #31.

In this commit the `README.md` has been updated and expanded to
cover all the backend available.
Change position of arguments of main

This is part of issue #31.

Just change the position of arguments of the script to make
easier for the user read it.
Grammar changes

* Some fix from @abelsiqueira.
* Add link to article from Elizabeth D. Dolan and Jorge J. Moré in arXiv.
Fix REQUIREMENTS

* Remove the perprof line.
* Change `==` to `>=`.
Merge branch 'doc' into 'dev'
Upgrade version number to 0.1.0

This close #31.

TODO for 0.1.1:

[ ] Add some tests

TODO for 0.2.0:

[ ] Add PDF and SVG as matplotlib possibles outputs (more
    information about it in matplotlib documentation. (We will
    not enable PS and EPS output because this are old formats)
Add black and white option

This cover #33.

A flag `--black-and-white` was add and change color lines to styles
(dashed and dotted).
Fix bug when file is in the current directory
Fix bug when using `--pdf` without `-o`

When not using `-o` the script will send the output to the screen
and because of it will not be possible to run LaTeX to produce the
PDF.

This fix this bug testing if both flags was set up.
Merge pull request #34 from r-gaia-cs/bw

Black and white
Merge pull request #35 from r-gaia-cs/bug

Fix `--pdf`