lsDS not compatible with DSLite

[ymarcon]

Because it calls for .GlobalEnv in place of parent.frame():
https://github.com/datashield/dsBase/blob/master/R/lsDS.R#L40

[StuartWheater]

Yes, it is on my "to do" list to ensure dsBase is fully comparable with DSLite. I plan to using dsBaseClient test suit to help with this, but will need to ensure all the test datasets are supported.