DeleteOptions#isRecurse incorrectly returns true

[sleberknight]

This is from the original consul-client issues list: Recurse to false in delete options not working

This return if the value is present, not if the value is true or false!
if you set the value to false, this returns true, so the query is send with recurse = true

Basically, DeleteOptions#isRecurse returns true when the Optional<Boolean> returned by getRecurse() is present, which means it returns true for both Optional<Boolean.TRUE> and Optional<FALSE>. Clearly it should actually test the value if the Optional contains one.

Also see #210