Interpret 'src' into 'data' or 'template'

Before processing the file list, see if the files in the list have a
'src' attribute. If so, automatically determine whether that 'src' is
for a list of templates or for data, and remap the object.
Tests for multiple JSON files into one template

Introduces unit tests that test the expansion method and the file map
method for inserting multiple different JSON data sources into a single
Mustache template.
Tests for multiple templates with one data source

Introduces unit tests that use multiple different templates but a single
data source file.
Update documentation

Adds usage examples for dynamically-build file lists.
Minor whitespace fixes

Corrects the indentation in the documentation and puts a missing
trailing double-space back into the markdown README.
Merge pull request #19 from corpulentcoffee/dynamic-files

Support dynamically building the file list using the built-in Grunt mechanisms