Remove caps locks and fix wording across CKAN and remove "Filters" title

[sachajudd]

Remove caps locks when editing the settings of a column and fix general typos:

Readable Name:

• [x] Readable label: #78

Visibility:

• [x] Show in results view (remove summary) #90
• [x] Show in detail view
• [x] Only show one value if duplicate exists #90

Presented order:

• [x] 2 of 26 columns (remove fields) #90

Please refer to designs for correct wording.

Remove "Filter" text: #90

• [x] Dropdown should only include the filters that read "Text" and "Dropdown".

Text filter settings:

• [x] Columns source(s): #78

  See designs

• [x] Also noticing an order field here that needs removing? #90

• [x] Remove unneeded gridfield title "Filters": #90

[robbieaverill]

It's worth mentioning that some of these are already fixed in the latest tip of master (see #78). I'll make a couple more tweaks now.

[robbieaverill]

I've tidied up the lowercasing of field labels logic a bit, so it can be removed again once SilverStripe 4.4 becomes the minimum requirement for this module, which would include https://github.com/silverstripe/silverstripe-framework/pull/8698 that does it by default.

Dropdown should only include the filters that read "Text" and "Dropdown".

We had the same problem with content blocks - it makes sense to refer to them outside of the UI context as "Content Block", "Form Block" etc, but in the UI you'd refer to them as "Content" and "Form" without the "Block". This led us to adding a second method for defining the name (the first being the i18n singular name) - and that led to developer confusion (see https://github.com/dnadesign/silverstripe-elemental/pull/502). Rather than do this again, I've just changed the singular names here. If it creates confusion in future we can revisit as an enhancement change.

[robbieaverill]

78 fixed some of these issues, #90 fixes the rest of them