revisit the recommended syntax for dataset IDs

[jvandegriff]

we want to allow and possibly encourage slashes in dataset IDs

Related ticket was ticket #89

[jvandegriff]

Verifier will need updating one we change the documentation.

[rweigel]

It would be useful to allow a way of indicating "hasParent" so a tree of datasets can be built.

#270

Add option to /catalog?

catalog?view=tree

Gives

DAS2 example of its tree representation, https://jupiter.physics.uiowa.edu/das/server?server=list, uses slash to delimit directories, which also end in /. A string describes each directory or dataset on the tree:

Juno/|Jupiter polar orbiter - Launch date 2011-08-05
Juno/Ephemeris/|Spacecraft position - Jet Propulsion Laboratory (NAIF)
Juno/Ephemeris/EuropaCoRotational|Juno Europa Co-Rotational orbit parameters
Juno/Ephemeris/GanymedeCoRotational|Juno Ganymede Co-Rotational orbit parameters
Juno/Ephemeris/Geocentric|Juno Earth orbit parameters
Juno/Ephemeris/Heliocentric|Juno Solar orbit parameters
Juno/Ephemeris/IoCoRotational|Juno Io Co-Rotational orbit parameters
Juno/Ephemeris/JSE_Attitude|Juno Jupiter Solar Ecliptic Pointing angles
Juno/Ephemeris/Jovicentric|Juno Jupiter orbit parameters
Juno/Ephemeris/Jupiter_Footprint|Juno Jupiter footprint and M-Shell
Juno/Ephemeris/Jupiter_Radial_SC|Unit vector from Jupiter's Jovicetric center to Juno, in spacecraft coordinates
Juno/FGM/|Fluxgate Magnetometer - Goddard Spaceflight Center (Jack Connerney)
Juno/FGM/ElectronCyclotron|Electron Cyclotron Resonance Frequency

level0 = spacecraft
level1 = quality
level2 = instrument
AC 
   H0
      MFI => AC_H0_MFI
      OR => AC_H0_OR
BAR
    H0