BUG-1281: optimize ControllerContext

- use a single instanceof of Splitter
- do not instantiate unneeded collections
- static methods should be static
- do not use string concat in LOG.error()
- do not use String.split()

Change-Id: I16d2232ab2f9ee86f64f7abc95d9b7ce073f0c22
Signed-off-by: Robert Varga <rovarga@cisco.com>
Merge "BUG-1281: optimize ControllerContext"