…ests

(MAINT) Enable acceptance tests for class-based resources

Prior to this commit, the instance_key method for the PowerShell Manager only partially
respected the uniqueness of a possible instance; if there are any differences between
two declarations in the path to the executable, arguments passed to the executable, or
the debug option, the manager would treat the new instance as expected, spinning up an
additional instance of the manager.

However, it completely ignored the pipe_timeout option, meaning specifying an instance
with a default pipe_timeout and a second instance with a pipe_timeout of 45 would
**actually** result in the second instance declaration just reusing the existing instance
with the default timeout, which is unwanted an unexpected behavior.

This commit modifies the logic for the instance_key method slightly by making the key a
concatenation of the path to the executable, the arguments, and the full options hash
turned into a string.

This both ensures that instance declarations with two different pipe timeouts are actually
both spun up as separate instances *and* enables a workaround for multi-threading:

Users will be able to specify an arbitrary option, such as instance_guid, which can uniquely
identify the instance for that thread. This should help folks keep the instances separated
and prevent weird behavior when calling the manager from multiple threads (though, of course,
this does mean that the multi-threading still has a spinup cost for each thread).

Related to/discovered in #180.

…e_key-uniqueness

(GH-180) Ensure instance_key respects full uniqueness of options

Mergeback 0.10.1 Release

When Protected Event Logging and PowerShell Script Block logging are
enabled together the SystemRoot environment variable is a requirement.

If it is removed as part of the environment purge it causes the
PowerShell process to crash, therefore breaking the pipe between Ruby
and the remote PowerShell session.

This commit fixes the issue by creating a filtered list of environment
variables which does not include the SystemRoot environment variable.

This list can then be purged safely.

(GH-188) Filter current environment variables

(MAINT) Release prep for 0.10.2