PSON serialization for `Resource::Status` missing time field

Prior to this commit, the PSON serialization for the class
`Puppet::Resource::Status` was missing the `time` field.  This
would result in `nil` values in reports, which was causing
failures in the PuppetDB report processor.  This commit
simply adds in the field to the serialization, and adds
corresponding test coverage.
Specify precision when serializing resource status time

The previous code for serializing the resource status' `time` field
to pson was not specifying the precision, and apparently Ruby's
default implementation truncates some of the value.  This minor
change allows us to keep the full precision.
Merge pull request #1746 from cprice404/bug/master/resource-status-pson-missing-timestamp

PSON serialization for `Resource::Status` missing time field