Fixed undefined modelClass when using polymorphic relations
Use `dist` property from swagger-ui package.

This removes the hardcoded local `node_modules` lookup for swagger-ui,
which will break if the parent installs swagger-ui itself.

This is useful if, for example, the latest swagger-ui breaks
loopback-explorer, and the parent project wants to install a fixed
version in its root.
Newest Swagger UI requires application/x-www-form-urlencoded.

UI will fail to POST if this consumes type is not specified.
Merge pull request #36 from nvdnkpr/master

Fixed undefined modelClass when using polymorphic relations
Merge pull request #37 from STRML/swagger-ui-dist

Use `dist` property from swagger-ui package.
Merge pull request #38 from STRML/form-encoding

Newest Swagger UI requires application/x-www-form-urlencoded.
Bump version
Merge branch 'release/1.2.9' into production
Merge tag 'v1.2.9'

1.2.9
Make sure nested/referenced models are mapped to swagger
add .idea to .gitignore
Make sure nested/referenced models in array are mapped to swagger

Signed-off-by: Clark Wang <clark.wangs@gmail.com>
Merge remote-tracking branch 'origin/feature/add-other-models'