Fix native type conversion in json_template

[ganeshrn]

Fixes #151

• The current json_template implementation tries to convert the value to int irrespective to the actual type of data.

• Ansible version 2.7 onwards supports native jinja2 types conversion. Refer https://github.com/ansible-network/network-engine/issues/151#issuecomment-427561789 eg: value: "{{ item.name.acl_name|float }}"

• To convert to native jinja2 type by default need to set jinja2_native config varaible in defaults section of active Ansible config file.

Note: This feature require jinja2 version to be >= 2.10

[softwarefactory-project-zuul[bot]]

Build failed.

• ansible-test-sanity : FAILURE in 3m 22s
• ansible-role-tests-devel-py2 : SUCCESS in 2m 01s
• ansible-role-tests-2.7-py3 : SUCCESS in 2m 04s
• ansible-role-tests-2.6-py2 : SUCCESS in 1m 55s

[softwarefactory-project-zuul[bot]]

Build succeeded.

• ansible-test-sanity : SUCCESS in 3m 29s
• ansible-role-tests-devel-py2 : SUCCESS in 1m 58s
• ansible-role-tests-2.7-py3 : SUCCESS in 2m 45s
• ansible-role-tests-2.6-py2 : SUCCESS in 2m 18s

[trishnaguha]

@ganeshrn We need to put this in Doc that this feature is only supported with Ansible 2.7 and requires jinja2 version to be >= 2.10. This cannot be backported. And example how one can still convert it into type int in the parser_template

[softwarefactory-project-zuul[bot]]

Build failed.

• ansible-test-sanity : FAILURE in 3m 47s
• ansible-role-tests-devel-py2 : SUCCESS in 2m 18s
• ansible-role-tests-2.7-py3 : SUCCESS in 2m 18s
• ansible-role-tests-2.6-py2 : SUCCESS in 2m 29s

[softwarefactory-project-zuul[bot]]

Build failed.

• ansible-test-sanity : FAILURE in 3m 25s
• ansible-role-tests-devel-py2 : SUCCESS in 2m 07s
• ansible-role-tests-2.7-py2 : SUCCESS in 2m 35s
• ansible-role-tests-2.7-py3 : SUCCESS in 2m 29s