Added Template Factory

[XedinUnknown]

Adds a template factory, which simplifies the process of creating templates for its consumers. It creates all factories with the specified evaluator implementation (through injected factory), default context, and custom functions. This allows all templates to share a common set of data, which can be overridden at render time, and of functions.

[mecha]

LGTM. Just seems to be missing some docs in the code; minor details.

[XedinUnknown]

Couldn't really find where the docs are missing. Could you kindly point out those places?

[XedinUnknown]

@mecha, please take a look at the readme.

[mecha]

Having forgotten the implementation, I read the README as a "new"-ish user wanting to learn how to use the library. Required multiple readings to get the gist of things. Here are some recommendations:

1. Start off with simple things: creating a template and rendering a template. Opening with factories right off the bat is pretty disorienting. Present the reader with the bare minimum, and then build up from there.
2. Demonstrate factories after point 1, showing off their benefits (like default ctx and functions).
3. The bullet list under "Usage" means nothing to the reader until they read the remainder of the file. I found myself reading it and thinking "wtf are $c, $f and uc?"
4. Avoid mentioning where code should be. Service definition, controller-level ... who cares?
5. I'd remove unnecessary syntax like service-ish functions or immediately-invoked functions. They're not relevant to the library and just make the demonstrated code look more complex than it should be. It doesn't do the library justice.

[XedinUnknown]

I'll improve the docs in a different PR.