Add limit on input field

[ARMmaster17]

Currently, there is no (theoretical) limit to what can be entered into the input field on the frontend. Should limit it to about 140 characters. In the future, could add recognition so that only one sentence is allowed (for better data accuracy).

[FreekingDean]

I opened this in JeffBot-Web FreekingDean/JeffBot-Web#1

Do you want to close this in favor of that?