Add animation menu+elements and formatting

These changesets add an animation tab in the main GUI that has the
bare-bone controllers as ported from E-vident SVN revision 253.

The formatter of the mapping file now selects which of the available
columns are numeric, if a column is numeric then it is saved else it is
not saved.
Fix problem with animatable metadata categories

The metadata map object was being used incorrectly, it should now work
just fine.
Add loading of animatable headers to the HTML
Merge branch 'master' of git://github.com/qiime/emperor into issue_150
Add combo boxes for the animation categories

The user can now select the category by which the trajectories will be
sorted and the category by which each category will be created.
Add base animation module to the JavaScript module
Base trajectory.js file
Add more work to the Trajectory manager

This module is starting to shape up but still needs a lot of work. This
commit serves to back this work up not to really make it production.
Add first implementation of data structure builder

This first implementation of the data-structure takes a mapping file and
a set of coordinates with the selected categories to build an object
with sorted elements by their position in the gradient.
Add getMinimumDelta utility to trajectory.js

This function will retrieve the minimum delta value for the available
trajectories in a dataset.
Comment out console.log calls
Add integration with trajectory.js

The AnimationDirector object is now capable of chewing the inputed data
with the help of some utility functions found in trajectory.js.

A couple other changes took place in this changeset:
    - Correct syntax errors for method declarations
    - Change documentation/comments to be more javascript compliant
    - Add some error checking to the constructor
Change identifiers for a couple of elements

A few elements were renamed to be consistent with their names in other
clases/modules, this should make it for a more readable/understandable
interface. Plus the needed callbacks were also added to the code-base.
Add utility functions to retrieve status variables

These variables represent the current frame being drawn, the total
number of elements that will be drawable, etc.
Integrate the animation director in emperor.js

This work still requires more debugging and cleanup but in this state
will animate over a single gradient-point.
Add underscore.js and license to the source

Underscore.js is an awesome tool, currently being used by animate.js and
by trajectory.js; a more extensive use of this module should be done.
Fix interpolated points generation

The interpolated points were being overwritten by the last segment
because the array of points were not being joined.
Make creation and manipulation of arrays better

The arrays are created only once but reset to length 0 per trajectory.
Add callbacks for the pause button
Cosmetic changes to make spheres smaller