Fix usage of is_false

Commit 8b2d53cd722590d6142872ca4b175b24ff7f8588 introduced an incorrect
usage of is_false, combining it with the [ function.  The is_false function
itself returns a truth value and does not need to be combined with [.  This
commit fixes the misusage.
Use is_true for CONF_OPTIONAL_REPO

Commit 8b2d53cd722590d6142872ca4b175b24ff7f8588 introduced checks against
CONF_OPTIONAL_REPO, which is a Boolean.  The added checks used the
[ function and the relational operator == to compare the value of the variable against
"1".  The correct operator is =, but anyway, we have the is_true function
for Boolean functions, which accepts more values that indicate truth, so
use is_true instead of [.
Use case/esac for CONF_INSTALL_METHOD

Instead of using an if/elif/elif/fi statement to test for different
values of CONF_INSTALL_METHOD, use a case/esac statement.
Correct documented default for CONF_INSTALL_METHOD

We do not actually set a default value for CONF_INSTALL_METHOD.  Leaving
it unset is equivalent to setting it to "none," and this is a reasonable
default, so correct the documentation to say that the default is "none."
Merge pull request #9 from Miciah/openshift.ks-fixes-20130308.1

openshift.ks fixes