Fix locale during package upgrade

When installing a package, concrete5 forces en_US. Let's do the same
also when upgrading an already installed package.
Localization for Url Slugs

Various change for locationation of url slugs
Keywords: remove duplicates, standardize format
Synchronize install and update keywords for 5.6.0
Add page keywords for new 5.6.1 page
Translate attribute key names
Translate attribute set names
Translate attribute key names only in view
Add missing attribute type names
Translate attribute type names
Translate permission key names
Translate access entity type names
Move block type translations to view
Merge pull request #1082 from mkly/condensed_urlify_commits

Localization for Url Slugs
Merge pull request #1087 from mlocati/intelligentsearch-i18n-v2

Dashboard keywords alignment for install & update
Merge pull request #940 from mlocati/fix-locale-during-package-upgrade

Fix locale during package upgrade
Merge pull request #1095 from mlocati/bmatzner_ui_translate_merge_v2

Revisited version of Bmatzner ui translate merge