fix(import): correct double directive import
feat(directive): Added anchor directive to prevent navigation when the anchor is empty.

Closes #112
chore(pub): Update with SDK 0.7.5
feat(annotations): refactored metadata extractor into injectable class
feat(Http): transformRequest, transformResponse
feat(http): AngularJS-style caching
fix(source_metadata_extractor): added support for ! attr map spec
feat(http): Setter for default headers