Code cleanup in uninstall / install

Uninstaller.java:
Removed runStarted field, replaced by UninstallProgressStep.STARTED.
Extracted methods putSummary(), removeRemoteServerReferences0(),
stopServer0(), disableWindowsService0(), deleteExternalDatabaseFiles0(),
deleteExternalLogFiles0(), deleteInstallationFiles0(),
handle(ApplicationException), notifyListenersBeforeStep(),
isReferenced().
Used static imports for UninstallProgressStep.

Application.java:
In getRemoteConnection(), removed parameters which where always the same
accross client calls and pushed them inside the method's body.