Implement hypertext cache pattern.

[petejohanson]

• withRepresentation now checks HYPERTEXT_CACHE_PATTERN flag and adds embedded resource's 'self' link to links with same rel.
• See https://tools.ietf.org/html/draft-kelly-json-hal-06#section-8.3

This depends on a small change to halbuilder-api I will be creating a pull request for momentarily.

[buildhive]

HalBuilder HAL API for the JVM » halbuilder-core #23 FAILURE Looks like there's a problem with this pull request (what's this?)