Use lodash on the server as well as the client

It seemed more than a little strange that we were using lodash on the
client side but underscore on the server side. So I fixed that.

I've also been a bit more honest about the lib we are using as lodash
does differ from underscore in places
Default axis config, merge module specific config

It would be great not to have to add this config to all of the JSON
files, so instead I've set some defaults (using Ben's work in
no-realistic) which can be overriden.
Merge pull request #246 from alphagov/default-axis-labels

Default axis labels
Clarify wording on site traffic module.

We had some user feedback that this could be improved.
Tighten up wording on Carer's Allowance dashboard.

Make minor text changes for neater wording on CA dashboard.
Change wording on GOV.UK trending module.

We had some user feedback saying that "increase" should be "percentage
increase" on the trending content list. This is true, so fixed here.

Also changed "greatest" to "largest".

Also make changes in no-realistic-dashboard, just for neatness.
a
Merge pull request #250 from alphagov/bugfix/minor-wording-changes

Minor wording changes on GOV.UK and CA dashboards
Add filtering to student finance dashboard