Final Local Variable Check, fixed false-positive - native method's param...

... should be declared final, issue #158

According to #158 

Fixed false-positive "Variable should be declared final" if it is param of native method (this case is similar to abstract methods in context of this Check)

1. Added UT and corresponding input for this case.
2. Extended method inAbstractMethod( ... ) to inAbstractOrNativeMethod( ... ) to let it catch these cases.
3. Added static modifier to inAbstractOrNativeMethod( ... ) to get rid of single warning in Check's class.