updated cookie serialization from hybrid to json, fixes #2255

Fix for making links have a higher color contrast to other text in blocks. (#2192) ...

The changes were based on the article  https://www.viget.com/articles/color-contrast/

Changes:
 - Link color has been  changed from #337ab7 to #107896.
According to https://webaim.org/resources/linkcontrastchecker/?fcolor=000000&bcolor=FFFFFF&lcolor=107896 (the "Link to Body Text" ratio is 4.14:1 and passes WCAG A test and "Link to Background" ratio is 5.06 and passes the 5.06:1 which satisfies WCAG AA test.)
- The TinyMce editor required new stylesheets to be created.

Fix for issue #1457

updated gems and yarn dependencies (#2179) ...

* updated gems and yarn dependencies

* updated yarn

* added csrf gem to deal with omniauth vulnerability

* add in explicit disable of non-post omniauth methods, add ignore statement tobundle audit so Travis can run the remaining tests

* replaced depricated Faker::StarWars with new Faker::Movies::StarWars

* downgrading timeago.js to 4.0.0beta.1 from *beta.2

swap pager_api for api_pagination due to jbuilder compatability

added plans fulltext api using pagination

Merge pull request #2131 from DigitalCurationCentre/feature/reviewer_role ...

fix label on share permissions for reviewer