Iteration on tables features

* renamed queryTable to tableQuery
* renamed create_table(...) to Table(...)
* replaced use of df.from_csv with the more general pd.read_csv
* enabled use of table IDs in some calls to create_table
* test handling of CSV files
* lots of null protection
* added --version argument to "synapse get"
* added _copyWiki(...)
Please add the 'recursive case', i.e. copying all wiki pages owned by one entity to another entity. (Use case is 'publishing' a tree of project wiki pages for a Challenge.)