Improve TLS 1.2 handling

[brianbunke]

Some JIRA installs enforce TLS 1.2 on the server side. This is good, and should be encouraged.

In this scenario, PowerShell 5.1 doesn't know what in the world is happening, and New-JiraSession fails with no helpful error message.

Furthermore, this module already includes a proxy function for Invoke-WebRequest, so that some of the new PowerShell version 6.0 functionality could be ensured. (See commit 81e12ff.) One of those features is new parameter -SslProtocol, which we should leverage, instead of new private function Set-TlsLevel. (See commit 9a5b636.)

Expected Behavior

New-JiraSession establishes a new JIRA session, regardless of security level.*

* - No opinion on whether users should be warned about insecure HTTP sessions, since JiraPS currently uses basic authentication on its API calls

Current Behavior

New-JiraSession fails if a TLS 1.2 session is enforced.

Possible Solution

In order of preference:

1. Seamless, transparent handling of TLS 1.2 connections
2. An exposed parameter on New-JiraSession to pass through -SslProtocol to the Invoke-WebRequest private proxy function

Steps to Reproduce (for bugs)

Enforce TLS 1.2 in a server installation's server.xml, then try New-JiraSession

Context

I fully support people trying to make their environments more secure by enforcing best practices. The module(s) should strive to support that whenever possible/feasible.

Related Issues (based on a quick search):

• New-JiraSession "You cannot call a method on a null-valued expression" #84
• New Server & Session handling #194

Your Environment

JIRA Server, 7.9 or 7.10
JiraPS 2.7
PowerShell 5.1