Upgraded amcrest to 1.1.8

[tchellomello]

Description:

• Upgraded Amcrest module to version 1.1.8
• Fixed traceback when reporting the used storage percentage.

Apr 08 14:26:32 ha hass[4466]:   File "/opt/srv/homeassistant/.virtualenvs/hass_venv/lib/python3.5/site-packages/homeassistant/helpers/entity_component.py", line 189, in async_add_entity
Apr 08 14:26:32 ha hass[4466]:     yield from self.hass.loop.run_in_executor(None, entity.update)
Apr 08 14:26:32 ha hass[4466]:   File "/usr/lib64/python3.5/asyncio/futures.py", line 380, in __iter__
Apr 08 14:26:32 ha hass[4466]:     yield self  # This tells Task to wait for completion.
Apr 08 14:26:32 ha hass[4466]:   File "/usr/lib64/python3.5/asyncio/tasks.py", line 304, in _wakeup
Apr 08 14:26:32 ha hass[4466]:     future.result()
Apr 08 14:26:32 ha hass[4466]:   File "/usr/lib64/python3.5/asyncio/futures.py", line 293, in result
Apr 08 14:26:32 ha hass[4466]:     raise self._exception
Apr 08 14:26:32 ha hass[4466]:   File "/usr/lib64/python3.5/concurrent/futures/thread.py", line 55, in run
Apr 08 14:26:32 ha hass[4466]:     result = self.fn(*self.args, **self.kwargs)
Apr 08 14:26:32 ha hass[4466]:   File "/opt/srv/homeassistant/.virtualenvs/hass_venv/lib/python3.5/site-packages/homeassistant/components/sensor/amcrest.py", line 149, in update
Apr 08 14:26:32 ha hass[4466]:     self._state = self._camera.percent(sd_used[0], sd_total[0])
Apr 08 14:26:32 ha hass[4466]: AttributeError: 'Http' object has no attribute 'percent'

Checklist:

If the code does not interact with devices:

• Local tests with tox run successfully. Your PR cannot be merged unless tests pass
• Tests have been added to verify that the new code works.

[mention-bot]

@tchellomello, thanks for your PR! By analyzing the history of the files in this pull request, we identified @fabaff, @balloob and @rmkraus to be potential reviewers.