Code cleanup.
Used EnvironmentConfig as a static import to configure JE.
BackendImpl.java:
Used EnvironmentConfig as a static import to configure JE.
Called getReadOnlyRootContainer() to remove duplicated code.
Extracted methods closeTemporaryRootContainer() and getEnvConfigForImport() to remove duplicated code.
In exportLDIF(), removed many redundant catch blocks and replaced them with only one for IdentifiedException.
javadoc cleanup.
ConfigurableEnvironment.java, Importer.java, ReplicationDbEnv.java:
Used EnvironmentConfig as a static import to configure JE.