(SET-37) Enable boolean values for offline param

    Previously, users needed to pass the string "true" to the
    profile::repos::offline parameter to achieve desired behavior; the
    boolean value True would not result in the base, updates, and other
    repositories being disabled.

    This commit modifies the profile::repos class such that any non-false
    value will correctly enable the behavior.

    We do not currently perform any type checking. Once type checking is
    built into the language, we can enforce that the value given is boolean.
    Until then for this code it makes more sense to keep it visually clean
    than to enforce boolean values.