Better handling of position option

For named parameters the position must be validated to both be an
integer and to be a valid index in an array. In other words, non-
integer values for the position parameter should raise an exception
and values for position which would result in an index less than
zero should also raise an exception.
Cleaning up test methods with setup

Moving instantiation of the Clerk::Template to an instance variable
created in the setup method.
Verbosity++

Improving readability by explicitly naming variables instead of
using single and shortened abbreviations.
Merge remote-tracking branch 'origin/base' into template-dsl
Removing test for Clerk V1 class.
Handling Grouped not last error

For the time being any grouped element template param must be the
last item added to the template because the parsing will be dumb.
Because of this, we need to ensure the named and ignored methods
cannot be called without raising an error.
Removing the accessor in favor of #to_a

It made more sense to me to represent the Template object as an
array using the #to_a convention rather than giving access to the
internal storage mechanism via an accessor.
Updating README with some guesses

The way Clerk is used has changed drastically. This is a first
stab at getting the README updated to reflect the new Templating
which also led to some tweaks for the rest of the usage of Clerk.
The sections about how to use parsing will have to be fleshed out
elsewhere.
Test enhancement for Clerk::Template

Adding test cases to ensure #named accepts strings and symbols
and that the grouped method requires an array as the second param.
Rdoc improvements
Yo dawg I heard you liked DSLs...

So I put a DSL inside your DSL so you could DSL while you DSL.
Merge branch 'template-dsl' of github.com:liftopia/clerk-gem into validations
ActiveModel validation support, hooray

- Added ResultSet to hold a single record of data, necessary for
  validators
- Flatten objects with groups
- Handle .valid? in Base by passing on to ResultSets
- Aggregate error messages from ResultSets
Turned the exception into a oneliner just cause.