Add base webhook

[jaumef]

References: #3
Added:

• Base Webhook
• Github Webhook
• Gitlab Webhook (init)
• Test data for:
  • Base Webhook
  • Base github events
  • Base gitlab events
• Updated readme
• Added Travis
• Added python requirements
  • Added requirements-dev.txt with mamba
  • Added requirements.txt

---

Tests (using mamba):

• Listener test
  • Instancer by payload
• Webhook test
  • Basic Data
• Gitlab webhook test
  • Basic Data
• Github webhook test
  • Basic Data
  • status

[XaviTorello]

@jaumef good work :)

Just some proposals to integrate on this PR:

• Isolate the class webhook and the dispatcher (the executable, the one that will "proxify" the hooks execution) to provide an easy way to ensure and simplify heritance.
• Provide an extended webhook object to clarify if it works as expected
  • i.e. _github extending webhook defining their own tests and actions to be done
• There are no test data for github hook (at testing test_hooks.py)

What do you think about it?

[ecarreras]

@jaumef we need the tests

[XaviTorello]

Related to #3 and #4

• Provide tests for each hook plz! ^^

[jaumef]

@ecarreras @XaviTorello Beware, tests are incoming 👍

[coveralls]

Changes Unknown when pulling b40fc33 on add_base_webhook into * on master*.

[XaviTorello]

Fixes #3 and closes #4

@jaumef 👍