Add Gladstone EA gauge to measurement collector

https://www.pivotaltracker.com/story/show/83031056 [#83031056]
Merge pull request #26 from sealevelresearch/add-gladstone-ea-gauge

Add Gladstone EA gauge to measurement collector
Add a -8cm offset to surge model predictions

https://www.pivotaltracker.com/story/show/83203594 [#83203594]
Merge pull request #27 from sealevelresearch/offset-surge-model

Add a -8cm offset to surge model predictions
Revert 8cm Z_0 adjustment
Merge pull request #28 from sealevelresearch/revert-8cm-offset

Revert 8cm Z_0 adjustment
Add extra config for EA scraper

- Chart datum offset, so we can translate from Newlyn
- Site Datum, to compare against that reported by the website and blow
  up if it ever changes.

https://www.pivotaltracker.com/story/show/83203118 [#83203118]
Merge pull request #29 from sealevelresearch/extra-config-ea-scraper

Add extra config for EA scraper
Add EA North Shields gauge

https://www.pivotaltracker.com/story/show/84221616 [Delivers #84221616]
Merge pull request #30 from sealevelresearch/add-north-shields-tide-gauge

Add EA North Shields gauge
Added ansible role of met-observatiosn-collector though with broken encrypted credentials
Fixed erroneous unicode character
Update API_URL and API_KEY encrypted vars

Note: Used HTTP (not HTTPS) - if HTTPS is available we should use it.