Made some Changes to the BMI plugin and Added JSONHelper class

@mlaszloffy @morgantaschuk @denis-yuen

Here is what the Pull Request contains:

* BatchMetadataInjection Plugin Modifications
 * Now validates against a schema before a json run is imported or when "validate-json-sequencer-run" parameter is entered
 * Added more tests for the plugin

* JSONHelper Class
 * Added helper class which uses jsontools-core as a dependency. Checks if a json is valid against a schema
* Added tests for the class