Add reprompt text functionality

[sjmog]

This should have the following interface, probably:

respond("Here's a thing!", reprompt: "Please say that again.")

Don't forget to add SSML support by wrapping in <speak> and stripping out any <speak> tags added by the user (see #12)

[VeronikaSalo]

Is this issue under already under construction? At least it marked like that in a Contributing section.

[mattrayner]

Hi Veronika, this is not currently under active development - it’s on my roadmap of features but haven’t been able to make a start yet Hopefully within a month I’ll have added this, unless you’d like to have a go?

…

On Fri, 25 May 2018 at 21:18, Veronika Salo ***@***.***> wrote: Is this issue under already under construction? At least it marked like that in a *Contributing* section. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#11 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ADVzNitFQYCG00CXHFyOSAb91DppsYlsks5t2GcxgaJpZM4SkJCz> .

[VeronikaSalo]

@sjmog @mattrayner I created a PR for the issue: #16