Make id optional in yaml serialization

Make the id optional for components in a yaml file to make authoring
yaml files easier. The id is only used for references in the yaml file,
ie if one component referes to another. The id isn't used for the
constructed component in the simulation anyways. In fact a new id is
generated when the component is constructed. So this change just makes
it easier to write yaml files, you don't need to include an id when it
isn't needed.
Fix property names in the Grid Performance Tests

Jenkins is complaining about the spaces in the test properties. The
names are changed here to camel case. Also, rename "Time (in s)" to
"Duration" to be consistent with the other performance tests.
Merge branch 'fix/grid-performance-xml' into 'master'

Fix property names in the Grid Performance Tests

+1: haizhouW, Wesley Turner, Harald Scheirich

Merged-on: https://www.assembla.com/code/OpenSurgSim/git/merge_requests/1375903
Merge branch 'feature/yaml-id-is-optional' into 'master'

Make id in yaml files optional

+1: haizhouW, Harald Scheirich, Wesley Turner

Merged-on: https://www.assembla.com/code/OpenSurgSim/git/merge_requests/1370903