Make it easier to use parameters in the API calls

[nbartels]

To make correct API calls we need sometimes query parameters to explain Meta what you really need. For example do you need the metadata, a special locale or some more/less fields.

Therefore we add some factory methods to our Parameter class to make this easier. Improve the code readability and beautiful.

For now 3 methods should be added:

• Parameter.withMetadata() to add the metadata
• Parameter.withFields(String fields) to define the returned fields
• Parameter.withLocale(Locale locale) to define the language of the returned data