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.
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
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.
Merge branch 'master' of git://github.com/qiime/emperor into issue_6
Update test for case with vectors

This test was failing because another branch was merged into the master
branch before this one.
Fix bug where --color_by would exclude items

When selecting only field A wit --color_by and then trying to add
vectors using field B and C the script would fail to recognize fields B
and C and exclude them from the analysis. Thanks for catching this issue
@antgonza.

A new enhacement has been added, now you can concatenate columns on the
mapping file using && for --add_vectors field.