Add a private constructor to utility classes

UpgradeUtil.java, Security.java, PrivilegeConstants.java, RoleConstants.java, OpenmrsUtil.java, OpenmrsConstants.java, OpenmrsClassScanner.java, FormUtil.java, OpenmrsClassLoader.java, MemoryLeakUtil.java, FormConstants.java, ExceptionUtil.java, DateUtil.java, DatabaseUtil.java, SchedulerUtil.java, SchedulerConstants.java, OrderUtil.java, NotificationConstants.java, SqlDiffFileParser.java, ModuleUtil.java, LuceneAnalyzers.java, ModuleConstants.java, ModuleFactory.java, HibernateUtil.java, MigrationHelper.java, ServiceContext.java, DefaultMessageSourceServiceImpl.java, Daemon.java, HL7Util.java, CachePropertiesUtil.java, HL7Constants.java, TestInstallUtil.java, WebModuleUtil.java, AllergyConstants.java, CustomDatatypeUtil.java, ValidateUtil.java

Background information:

Utility classes, which are a collection of static members, are not meant to be instantiated. Even abstract utility classes, which can be extended, should not have public constructors.

Java adds an implicit public constructor to every class which does not define at least one explicitly. Hence, at least one non-public constructor should be defined