Merge branch '3.1'

Conflicts:
	.travis.yml
	code/controllers/ReportAdmin.php
Merge branch '3.1'
Move CMSMain->generatePageIconsCss() into a LeftAndMain extension (fixes #798)
Merge remote-tracking branch 'origin/3.1'

Conflicts:
	.travis.yml
	templates/Includes/ReportAdmin_Content.ss
	templates/ReportAdminForm.ss
Translations: Switch to Transifex format

- Based on new (last) translation download from getlocalization.com
- Removed untranslated strings. Getlocalization started including those at some point
which is highly annoying, unnecessary and breaks the new transfix system,
since it'll mark all of the english strings as actual translations
- Avoid dots in entities. It confuses the Transifex YML parser
- Removed some locales unknown to Transifex which didn't have any translations anyway
- Renamed "lolcat" locale from "lc_xx" to "en@lolcat" (Transifex/CLDR notation)
- Renamed "Te Reo/Maori" locale from "mi_NZ" to "mi" (Transifex/CLDR notation)
- Namespaced all entities used in templates (deprecated usage)
- Converted dots to underscores where template filenames are used for namespaces,
since Transifex YML parsing handles them as separate YML keys otherwise
- Removed whitespace in entity names, SilverStripe i18n can't handle it
Merge remote-tracking branch 'origin/3.1'

Conflicts:
	lang/en.yml
Merge remote-tracking branch 'origin/3.1'
Updated translations
Fixed share instructions wording in template

This also removed all the existing translations from Transifex
because the string changed.
Merge remote-tracking branch 'origin/3.1'
Merge remote-tracking branch 'origin/3.1'
AssetAdmin: PHP warning trying to add empty values into CompositeField

If the logged in user doesn't have permission to add a Folder record,
AssetAdmin::getEditForm() tries to enter an empty value into the
children of a ComposteField. This breaks SSViewer with a
call_user_func invalid args PHP warning.

Only include these buttons when they're available to the user.
"add page" behaviour fixed to work with new FormField IDs (#786)
Merge pull request #840 from halkyon/compositefield_assetadmin_warning

AssetAdmin: PHP warning trying to add empty values into CompositeField
FIX SiteConfig scrollbars visible
Merge pull request #802 from tractorcow/3.1-condition-fix

BUG Fixed up SQL table.column identifiers, SQL encoding issue
Merge pull request #842 from ARNHOE/3.1-siteconfigfix

FIX SiteConfig scrollbars visible
FIX: GridField button styling in reports
Merge pull request #843 from nedmas/patch-1

FIX: GridField button styling in reports
Search callback for "add page" selector

Necessary since we now default $showSearch=true in TreeDropdownField.
See https://github.com/silverstripe/silverstripe-framework/pull/2364