Split out project list head and body into partials
Add configure button for choosing columns to include in 'My plans' list
Use helpers to generate 'My plans' headings and content - another step on the way to making the columns user-configurable
Initial attempt at adding the column chooser.
Choose a more descriptive and non-conflicting name for the checkbox html options
Move configure button out of table head so it doesn't conflict with tablesorter
Move configure buttons to the left to match button position on other table
Allow users to select columns shown in 'My plans'.

This stores the desired columns in the session for now, which
is not desirable.

There is also a rudimentary user settings setup, which may be
duplicated effort and so may need to be removed.
Use rails-settings to store plan-list column settings
Disallow unknown columns
First attempt at configuring columns with JS
Make config cog orange
Allow default settings to be resolved
Add disabled 'Select an action' option
Simplify column header helper by providing locale entries for all column titles
Use I18n instead of #humanize for column titles in settings
Merge @uoldmp's implementation of custom columns for My Plans

Manual merge required, with some of the changes superseding the most
recent ones to /app/views/projects/index.html.erb made in
https://github.com/DigitalCurationCentre/DMPonline_v4/commit/e1d5e33070c
e2dc54081ced5a937f1df5aca6572 by @martaribeiro. Changes accepted due to
significant nature of change to “My Plans”.