WIP: Allow hsls to be used as a library

[joeykleingers]

Allows the hsls program to be used as a library.

• Factored out the hsls algorithm into its own method (_execute)
• Created two library methods (listDomainContents and listDomainsContents) which allow outside code to call the hsls algorithm, either with one domain or multiple domains. Rather than have tons of configuration parameters in the library method signatures, I also created a small class called HSLS_Params that encapsulates all the possible parameters that can be passed into the library methods. The library methods override Config values with their own parameter values if those parameter values are not set to None. In this way, the caller of the methods can run the algorithm with their own parameters regardless of what config values are set (or choose to use the Config values by setting parameter values to None).
• Created a parsing method (parseCmdLineArgs) that parses the args coming in from the main method and adds them to the Config object.
• Updated main method to just call parseCmdLineArgs and then call _execute.

Using this PR, we are now able to call the hsls algorithm directly from a HyperThought endpoint. Without it, we would have to spawn a subprocess to call hsls via the command line, which has its own security and technical issues.

Signed-off-by: Joey Kleingers joey.kleingers@bluequartz.net

[jreadey]

I had an offline conversation with Joey about this PR. Joey wasn't aware of the Folder class in h5pyd, so he'll be reviewing that to see if it would make more sense to add capabilities to Folder rather than creating a library for hsls.