Support for booleans, dates, ints, floats, and JSON

[auxesis]

jseql currently supports encrypting and decrypting text.

Other data types like booleans, dates, ints, floats, and JSON are extremely well supported in other CipherStash products. EQL (which jseql is built on top of) supports all of these data types.

All of EQL's data types should be exposed in jseql.

[coderdan]

#190 adds support for number and opaque JSON types.