Fix to support JSON/JSONB/JSONPATH datatypes

[shabbir10july]

JIRA: #42

Problem: Two new datatypes are introduced in NPS: JSON and JSONB. The support of these two datatypes on the server-side requires some changes on the client-side so it can retrieve JSON/JSONB data from the server.

Solution:

1. Enabling nzpy client to send its client version string 'Release 11.1.0.0' to the server at the beginning of each session, which tells the server that nzpy client is capable of handling JSON/ JSONB data. Notice: the client version string must start with a string, such as 'Release', in order for the server to properly parse it.
2. Mapping JSON/JSONB data to string type in nzpy, which can be handled in a similar fashion as NVARCHAR data in nzpy.

Testing: Ran an application which fetches JSON and JSONB datatypes. Results attached in JIRA.
Ran test suite 'pytest -vv tests/test_typeconversion.py'