Add basework for --add_vectors

Add sanity checks for the values this option can take from the script
interface.

Change the way some checks were being performed for --custom_axes where
an unexpected error could be raisen with a non-informative error
message.
Add format_vectors_to_js and test case

Add a function to convert the input data into a javascript formatted
dictionary where vectors are contained. As well as a couple test cases.
Merge branch 'master' of git://github.com/qiime/emperor into issue_6
Change indentation from spaces to tabs
Fix bug in format.py for sorting column

The reduced mapping file was not looking explicitly for the location of
the sorting column but rather working under the assumption that it would
be the second column.
Merge branch 'issue_58' into issue_6
Add formatting of the javascript objects

The script can now functionally create the vector javascript objects
when the appropriatte parameters are passed and create only an empty
javascript object when no vector-related options are passed.
Merge branch 'issue_9' into issue_6
Add functionality to be able to draw vectors

The functionality to draw vectors from the g_vectorPositions array is
now in place.

A new function has been added to serve as a utility to create
two-vertices lines, so far all of the line-elements in Emperor have this
definition, so this comes in real-handy.

Fixes #6
Merge branch 'master' of git://github.com/qiime/emperor into issue_6
Add script usage examples for the vector cases
Add vectors formatting for the footer

The footer now adds a slider for the opacity of the vectors when needed
Add callbacks for the opacity vector slider

Add support for the opacity of the vectors changing via the slider in
the main GUI.
Add splash screen elements

Add a table at the top of the document that holds the logo for emperor
in it. This table is hidden once the metadata-mapping file and
coordinates javascript objects are loaded.

Fixes #33
Add favicon to index.html

Logos are of course original creations of @meganap
Change __version__ and __copyright__ strings

All files point to the same version and copyright now
Add filtering module and test suite

This module contains functions to remove samples from coordinates data,
which is a non-practical thing to do, hence the warning in the script
interface.
Fix with --ignore_missing_samples & --custom_axes

When passing --ignore_missing_samples and trying to add a custom axis,
the lack of samples in the coords data would make the data in the
mapping file not match the dimensions of the data in the PCoA data.

Change the default value for --add_vectors and change the contition for
the formatting of the footer.

Change __copyright__ string
Add usage example and description to README.md

INSTALL.md was also updated to add download instructions.
Fix error in test data array initialization

The array was being initialized in a non-valid format for NumPy 1.5.1
this format however was valid for 1.6.1, it has now been corrected.