Re-add ApiProperty.dataType which was accidentally removed with 3f95978b

As of 3f95978b, compilation fails with the message:
  SwaggerJsonSchemaProvider.scala:205: error: value dataType is not a
  member of com.wordnik.swagger.annotations.ApiProperty

This commit re-adds the dataType field and now it builds and all tests
pass.
Merge pull request #147 from shawnlauzon/fixApiProperty

Re-add ApiProperty.dataType which was accidentally removed with 3f95978b
fixed response headers
added headers
updated to play 2.1
added per #149
updated to use utf-8
fix for #142
fix test failure
[maven-release-plugin] prepare release swagger-project_2.9.1-1.2.1
[maven-release-plugin] prepare for next development iteration
added support for @JsonProperty and @JsonIgnore per #152