Adding support for dialogs

[hwz]

• support for dialog responses
• added dialogs blurb in readme

Summary

Describe the goal of this PR. Mention any related Issue numbers.

Requirements (place an x in each [ ])

• [x] I've read and understood the Contributing guidelines and have done my best effort to follow them.
• [x] I've read and agree to the Code of Conduct.

[codecov[bot]]

Codecov Report

Merging #20 into master will decrease coverage by 4.29%. The diff coverage is 3.12%.

@@            Coverage Diff            @@
##           master      #20     +/-   ##
=========================================
- Coverage    36.8%   32.51%   -4.3%     
=========================================
  Files           3        3             
  Lines         144      163     +19     
=========================================
  Hits           53       53             
- Misses         91      110     +19

Impacted Files	Coverage Δ
src/express-middleware.js	15.38% <0%> (-0.84%)	:arrow_down:
src/util.js	54.54% <0%> (-45.46%)	:arrow_down:
src/adapter.js	36.28% <6.66%> (-4.32%)	:arrow_down:

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