BlogSession: changed 'role' to 'roles', an array of possible values; and
updated constructor(s) to allow more possible values, e.g., it can be
"author" or "reader" or both.
ForumSession: changed language_list to languange_lists; and allowed (in
rare cases) more than one language to be specified; similarly, more than
one download_version is possible (rarely) - although only the last one
is kept, the download_count increments each time, so it may be more than
1.
SessionBase.addProperty: modified to accept any Object value, not only a
String (hence, an array of String is now possible).
JSONClient: updated to include more JSON examples, including those for
SET_FIELD, and for FIELD using dot and bracket (sub-object and array)
notation. In particular: added lots more queries to be run; added a
(private) runQuery method, to remove some of the repetitive code;
updated 'last-login' to be an integer, not a String; added a new
'voltdb2' user, and tweaked the definition of 'voltdb'.
JSONClient: just split some query lines that were way too long.
JSONClient: added two queries, identical to existing ones, but
demonstrating different ways of doing things: one uses field(field(…))
rather than field(foo.bar); the other uses array_element(field(…))
rather than field(foo[0]). Also added a comment, "(combines dot and
bracket notation)", the first time we do that. And removed one
extraneous table.advanceRow() call.
Merge pull request #1769 from VoltDB/ENG-6876-json-example

Eng 6876 json example: Paul has reviewed the code, including with the two additional queries I added at John P.'s suggestion, so I'm merging this to master.