Pass Company custom properties in the main company json object
FIX: Date and numeric data
Update pom.xml
Refactoring some code

* Change JsonSerializer<Company> implementation to use JsonSerializationContext.serialize()
* Convert TAB indent to SPACE indent
* Remove irrelevant .gitignore setting
Add test cases of Company serialization/deserialization
Merge pull request #2 from olmeras/master partially.

Fix #1 issue that company custom data is not correctly serialized.
Pull request from olmeras/master is partially merged and modified
via fix/invalid-company-custom-data branch.