Refs #4611 - rake-ify foreman-config and db_pending_migration/seed in settings

This way, we can determine in the installer if the rake
db:migrate/seed should be run in the installer.

Later, we also could use this information to inform the entering user
that the application is not in ready state yet: preparation for
maintenance page.
fixes #5922 - compute resource #random_password to use SecureRandom()
fixes #7772 - avoids multiple ajax requests

the two-pane (and others) triggers the onContentLoad event, removing the
data attribute from the DOM will ensure its not loaded more than once.
Refs #3809 - Remove rubocop TODOs

Removed the following TODOs so that cops for these will run from now on:

Lint/AmbiguousOperator, DefEndAlignment, DeprecatedClassMethods
EnsureReturn, RequireParentheses, Void, BlockAlignment, EndAlignment,
UselessAccessModifier,

Style/IndentArray, IndentHash, Tab, UnlessElse, UnneededPercentQ, UnneededPercentX
RedundantReturn

Rails/Validation
Refs #3809 - Fix a few rubocop TODOs