* Refactoring RequestTemplate to RFC6570
This change refactors `RequestTemplate` in an attempt to
adhere to the [RFC-6570 - URI Template](https://tools.ietf.org/html/rfc6570)
specification more closely. The reason for this is to
reduce the amount of inconsistency between `@Param`, `@QueryMap`,
`@Header`, `@HeaderMap`, and `@Body` template expansion.
First, `RequestTemplate` now delegates uri, header, query, and
body template parsing to `UriTemplate`, `HeaderTemplate`,
`QueryTemplate`, and `BodyTemplate` respectively. These components
are all variations on a `Template`.
`UriTemplate` adheres to RFC 6570 explicitly and supports Level 1
(Simple String) variable expansion. Unresolved variables are ignored
and removed from the uri. This includes query parameter pairs. All
literal and expanded variables are pct-encoded according to the Charset
provided in the `RequestTemplate`.
`HeaderTemplate` supports Level 1 (Simple String) variable expansion.
Unresolved variables are ignored. Empty headers are removed. No
encoding is performed.
`QueryTemplate` is a subset of a `UriTemplate` and reacts in the same
way. Unresolved pairs are ignored and not present on the final
template. All literals and expanded variables are pct-encoded
according to the Charset provided.
`BodyTemplate` supports Level 1 (Simple String) variable expansion.
Unresolved variables produce empty strings. Values are not encoded.
All remaining customizations, including custom encoders, collection format
expansion and charset encoding are still supportted and made backward
compatible.
Finally, a number of inconsistent methods on `RequestTemplate` have
been deprecated for public use and all deprecated usage throughout
the library has been replaced.
Files had various formatting differences, as did pull requests. Rather than
create our own style, this inherits and requires the well documented Google
Java Style.