Merge branch 'release/v0.1.1' into develop

* release/v0.1.1:
  Bumping version to 0.1.1
Fixing php versions in travis config
Adding initial spec and class for Message/SlashCommand
Adding static create() method to Phlack\Phlack
Ensuring error responses are returned instead of Exception being thrown
Updating README.md

Adding some basic documentation
Merge branch 'feature/commands' into develop

* feature/commands:
  Updating README.md
  Ensuring error responses are returned instead of Exception being thrown
  Adding static create() method to Phlack\Phlack
  Adding initial spec and class for Message/SlashCommand
Removing version from composer.json
Adding v0.1.2 to Changelog
Merge branch 'release/v0.1.2'

* release/v0.1.2:
  Adding v0.1.2 to Changelog
  Removing version from composer.json
  Updating README.md
  Ensuring error responses are returned instead of Exception being thrown
  Adding static create() method to Phlack\Phlack
  Adding initial spec and class for Message/SlashCommand
  Fixing php versions in travis config