openshift.ks: Refactor high-level install steps

Factor the steps at the end of the script into a new configure_all
function, and call that function after parse_cmdline and set_defaults.

Modify the generation rules for generic/openshift.sh to take this change
into account.
openshift.ks: Rename parse_cmdline

Rename parse_cmdline to parse_kernel_cmdline.
openshift.ks: Refactor parse_kernel_cmdline

Factor parse_args out of parse_kernel_cmdline.
openshift.sh: Parse command-line args

openshift.ks: Add a parse_cmdline function that parses the command-line
arguments.  Add a commented-out invocation of parse_cmdline.

scriptify, Makefile: When generating openshift.sh and openshift-amz.sh,
disable the invocation of parse_kernel_cmdline and enable the invocation of
parse_cmdline.

With this commit, it is now possible to specify settings as arguments
instead of environment variables.  For example, instead of the following:

    export CONF_DOMAIN=example.com
    sh openshift.sh

Now it will be possible to do the following:

    sh openshift.sh domain=example.com
openshift.ks: Add CONF_ACTIONS

Add the CONF_ACTIONS setting, using which the user can specify
a comma-separated list of functions to run.

Assign CONF_ACTIONS the value configure_all by default.

Don't run configure_all unconditionally.  Now the user can override the
default installation process to provide a list of steps to run or even
specify only one action to run, for example to reconfigure a single
service.
Merge pull request #46 from Miciah/openshift.ks-refactor-arguments-parsing

openshift.ks: Refactor arguments parsing
don't use perl in install scripts as it's not present in the RHEL minimal install
ensure ntp and ntpdate rpms are present if required, not present in the RHEL minimal install
Merge pull request #48 from Miciah/openshift.ks-yum-install-ntp-ntpdate

openshift.ks: yum install ntp ntpdate
Merge pull request #47 from Miciah/openshift.ks-replace-perl-by-sed

openshift.ks: Replace perl by sed