Forms

[rockwellll]

This PR allows for more control of the form's success message, previously when a form was completed, it dispatched a form:completed event and removed itself from the DOM.

[Deprecated] Configuration options

It removes the autoMountForms from the top-level config object when initializing the library.

[New] Configuration options

It replaces removed autoMountForms and replaces it with an object that accepts the following attributes,

Hellotext.initialize('HELLOTEXT_BUSINESS_ID', {
  forms: {
    autoMount: true,
    successMessage: 'Thank you for submitting the form'
  }
})

It updates the readme as well to highlight new configuration options.