jmespath-0.3.0

This release contains Gson support (see #32, this was released in 0.2.1, but should have been in this version), improvements to how function calls are handled, with arity checking at compile tile (see #27), support for variadic functions (see #36), performance improvements (see #44), the possibility to make functions return null instead of throw exceptions on type errors (see #26) and improvements to the Jackson runtime (see #40).

Thanks to all contributors, and sorry for the time it took to get this release to happen.