Uptime module for tax collection service

@maxfliri, @YolinaS
Removing unused option from availability module

@YolinaS, @maxfliri
Feature test for response time module
Test uptime and response time modules in one scenario

For faster execution and less duplication

@YolinaS, @maxfliri
Merge branch 'master' into evl-availability-modules
Refactor feature tests for service availability modules

This reflects the fact that we now have a single availability module
that contains both uptime and response time, and allows testing for
dashboards with more than one availability module

@YolinaS, @maxfliri
Remove ids from availability module markup

This is to allow multiple availability modules on one dashboard

@YolinaS, @maxfliri
Add SORN availability module to evl dashboard

@YolinaS, @maxfliri
Load tax-disc and sorn monitoring from different buckets

@YolinaS
@maxfliri
Apply specific id to tax disc availability module

@YolinaS, @maxfliri
Rename electronic vehicle licensing to vehicle excise duty

@YolinaS
@maxfliri
Include js overview controller for evl into build.js

@YolinaS, @maxfliri
Feature toggle for evl availability modules

@YolinaS, @maxfliri
merge master into evl-availability-modules
Merge pull request #152 from alphagov/evl-availability-modules

Add availability modules to EVL dashboard (now called "Vehicle excise duty")