[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.
fixed ProductOrder pojo
enabled VirtualGuestClientLiveTest.testCancelAndPlaceOrder
fixed ProductItemsTest
fixed ProductItemToImageTest
fixed DatacenterClientLiveTest
fixed ProductPackageClientLiveTest
fixed VirtualGuestClientLiveTest
addressed mattstep's comments
addressed demobox's comments
applying aled's patch
added getActivePackagesReduced and adapted code accordingly
addressed remained comments
addressed demobox comments
more comments addressed