[JCLOUD 301]: Make increased use of Invokable params cache

This patch moves the Invokable Parameter cache to Reflection2 and adds
a convenience method for it to allow it to be shared by multiple
callers. The subsequent ability of S3Utils to use this cache results
in a ~40% improvement in performance for generating signed GETs and
PUTs for S3. This commit also converts a few others calls to
Invokable.getParameters() but the observed benefit from those was
small in microbenchmarks.
Renamed variable and method more appropriately.
Fixed imports and formatting.