Add declaration files for TypeScript support

[samuelastech]

My TypeScript project needed to use getContext feature so I write a declaration for it inside @types folder and indicate this in package.json.

Without it, we always will get an error (Could not find a declaration file for this module) when importing reverso-api in a TypeScript file.

Reference: DefinitelyTyped

File	Purpose
index.d.ts	This contains the typings for the package.
reverso-api-tests.ts	This contains sample code which tests the typings. This code does not run, but it is type-checked.
tsconfig.json	This allows you to run tsc within the package.
tslint.json	Enables linting.
.eslintrc.json	(Rarely) Needed only to disable lint rules written for eslint.

[yassine-safraoui]

are you guys here?