Consider optimising Scope internals

[Vladimir Dzhuvinov]

Use original string to store values instead of hash set

[Vladimir Dzhuvinov]

Parsing optimised to use StringTokenizer instead of String split(), resulting in two-fold performance increase.

Still open on using a string for the internal value representation, need more tests and experience from practice (replicated authz store).

[Vladimir Dzhuvinov]

Decided that no further optimisation is needed at this point.