Tests of Elytron utils

Created tests of Elytron utils. Tests of Base64 incomplete - only B variant. Others variants I postpone for now because I didnt found any specifications of it.

**Other changes:**

* `ByteArrayIterator`/`CharacterArrayIterator` - changed throwed exception after discussing with David: (depending classes changed to throw same exception as before - `InvalidKeySpecException`)

>Aug 29 16:48:54 \<dmlloyd>	no that class is public now
>Aug 29 16:49:12 \<dmlloyd>	so it should use NoSuchElementException *or* ArrayIndexOutOfBoundsException
>Aug 29 16:49:14 \<dmlloyd>	either one
>Aug 29 16:49:31 \<dmlloyd>	since it's public, it cannot be assumed that it is being used to iterate a key spec

 * Unused method `current()` of same classes removed - its name is confusing, because it doesnt return current item, but previous. (If you dont agree, comment)

* `Arrays2` - renamed parameter offs to offs1 to express of which array this offset is.