[IDEA] Use standard configuration options for HTTP Client

[mgaffigan]

Using non-standard HTTP client configuration creates a tripping hazard to anyone new to mirth. Unless I'm mistaken, all functionality already exists in normal java http configuration options.

Current behavior:
Administrators have limited ability to control HTTP Client using standard configuration options. Deployment behind proxies and reverse proxies is also limited by the requirement to use HTTPS, which is inappropriate for many modern deployment and development circumstances. Future SSL "best-practice" requires code changes.

Desired behavior:
By default, respect standard Java options for HTTP Client, and only use non-system-default HTTP options when explicitly configured on a channel with exposed UI.

Considerations:
Keep a secure-by-default posture in the quick-start setup installer.