Optimize string splitting by using Splitter class

Instead of performing costli String.split() operation, instantiate a
shared Splitter and use it to split the string. Requires slight
alterations to logic, but those are rather obvious.

(cherry picked from commit 0326de0142122b44aef3d4b2ed94e64ab2378dbb)
Signed-off-by: Robert Varga <robert.varga@pantheon.sk>
Signed-off-by: Michal Rehak <mirehak@cisco.com>
Change-Id: I801cdaf9500b6ec877a1fc8af94b9e4b9bcc7635