Suggest change the "network" default value to "udp"

[taotod]

Snap daemon version (use snapteld -v): 1.2.0

Environment:

• Cloud provider or hardware configuration: VM OS run on EXSi 6.0
• OS (e.g. from /etc/os-release): PRETTY_NAME="Ubuntu 16.04.1 LTS"
• Kernel (e.g. uname -a):Linux ubuntu-snap-node1 4.4.0-83-generic #106-Ubuntu SMP Mon Jun 26 17:54:43 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux
• Relevant tools (e.g. plugins used with Snap):snap-plugin-collector-snmp
• Others (e.g. deploying with Ansible):

What happened: I notice that the value of "network" of task1.json and task2.json files is "tcp" rather than "udp". Generally, SNMP is based on UDP. Should we change its default value to "udp"? When I use the SNMP plugin to manage some devices, the communication can't be created because I don't change the "network" value. After I change it to "udp", everything works well.

What you expected to happen: it is better set the default network type to udp

Steps to reproduce it (as minimally and precisely as possible): Just a configuration concern. No steps to reproduce.

Anything else do we need to know (e.g. issue happens only occasionally):