v0.2.0 - Support query request

The SphereClient supports now query requests with related query parameters.

// example

var sphere_client = new SphereClient({...})
sphere_client.products
.where('name(en="Foo")')
.where('id="1234567890"')
.whereOperator('or')
.page(3)
.perPage(25)
.fetch()

// HTTP request
// /{project_key}/products?where=name(en%3D%22Foo%22)%20or%20id%3D%221234567890%22&limit=25&offset=50