Unit tests

Clean out useless code from ServerResponse.
Fix ServerResponseTest.

Remove entity reflect method and replace it by saving the raw data array which will be used for returning JSON string.

Save raw JSON response to ServerResponse object.

Small optimisation for Chat entity.

Rename stripMarkDown to escapeMarkdown to give it more sense.

[skip ci]

* upstream/develop:
  implement getWebhookInfo method
  Fix duplicate test case
  Add test for unit testing class Entitiel/User
  Move AudioTest.php from tests/Unit* to tests/unit*
  Fix error importing class TestHelpers
  Correcting grammatical errors
  Add unit test for Audio class
  Add helper method generate fake audio recorded data
  Add dependency for ext-mbstring, as suggested by @IronLady in #92 [skip ci]

implement getWebhookInfo method

Also free some bugs!

Some typos, code cleanup.

Unit tests for Audio and User entity.
Thanks a lot @monster3d 

Change interpretation of keyboard parameters, so that each parameter represents a button on it's own row.