Wrong member name, must be elementClass

[Pedro Casaubon]

begin working with the api, get this error:

"UnhandledPromiseRejectionWarning: TypeError: childClass.elementClass is not a constructor"

I think is a typo error.

node-lokalise-api/src/collections/files.ts

Line 10 in 725240d

 protected static memberClass: Object = File; 

needs to be:

protected static elementClass: Object = File;

[Roman Kutanov]

Thank you!