v0.0.1-alpha

This is the first functioning version of Pebble. The following has been implemented:

• tags: block, extends, for, if, import, include, macro, set
• filters: abbreviate, capitalize, date, default, format, json, lower, number, trim, upper, urlencode
• functions: block, parent
• tests: empty, even, null, odd, iterable, equalTo
• operators: in, is, is not, +, -, /, *, %, and, or, (), ==, !=, <, >, <=, >=, |, .
• unit tests