Move install script error handling to a common function

All of our install/admin scripts had a try/except block calling the
main function and handling common exceptions. These were copy-pasted
from each other and modified to various levels of sophistication.
This refactors them out of installers to a single function, which
includes a final pass/fail message for all of the scripts.

Non-install scripts that set up the same log handler levels for
stderr and log file are not changed, as it's not possible to log
to only the logfile without changing the logger configuration.

https://fedorahosted.org/freeipa/ticket/2071

install/tools/ipactl

@@ -21,10 +21,10 @@
 import sys
 try:
     import os
-    from ipaserver.install import service
+    from ipaserver.install import service, installutils
     from ipapython import services as ipaservices
     from ipaserver.install.dsinstance import config_dirname, realm_to_serverid
-    from ipaserver.install.installutils import is_ipa_configured, wait_for_open_ports, wait_for_open_socket
+    from ipaserver.install.installutils import is_ipa_configured, wait_for_open_ports, wait_for_open_socket, ScriptError
     from ipapython import sysrestore
     from ipapython import config
     from ipalib import api, errors
@@ -44,13 +44,8 @@ error was:
 
 SASL_EXTERNAL = ldap.sasl.sasl({}, 'EXTERNAL')
 
-class IpactlError(StandardError):
-    def __init__(self, msg = '', rval = 1):
-        self.msg = msg
-        self.rval = rval
-
-    def __str__(self):
-        return self.msg
+class IpactlError(ScriptError):
+    pass
 
 def check_IPA_configuration():
     if not is_ipa_configured():
@@ -386,17 +381,6 @@ def main():
     elif args[0].lower() == "status":
         ipa_status(options)
 
-try:
-    if __name__ == "__main__":
-        sys.exit(main())
-except IpactlError, e:
-    if e.msg:
-        emit_err(e.msg)
-    sys.exit(e.rval)
-except RuntimeError, e:
-    emit_err("%s" % e)
-    sys.exit(1)
-except SystemExit, e:
-    sys.exit(e)
-except KeyboardInterrupt, e:
-    sys.exit(1)
+
+if __name__ == '__main__':
+    installutils.run_script(main, operation_name='ipactl')