Allow supervisord environment vars to have "="

[stephenyeargin]

Prior to this PR, an environment variable configured for use with Foreman could not contain a ?, = or & (common in URLs) if the target configuration was set to SupervisorD. This PR cleans up the output from Shellwords.escape in order to be ready for use in a app*.conf file. I've updated the tests to cover this particular issue.

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From the documentation for Shellwords

Note that a resulted string should be used unquoted and is not intended for use in double quotes nor in single quotes.

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From the documentation for SupervisorD

A list of key/value pairs in the form KEY="val",KEY2="val2" that will be placed in the child process’ environment. The environment string may contain Python string expressions that will be evaluated against a dictionary containing group_name, host_node_name, process_num, program_name, and here (the directory of the supervisord config file). Values containing non-alphanumeric characters should be quoted (e.g. KEY="val:123",KEY2="val,456"). Otherwise, quoting the values is optional but recommended. Note that the subprocess will inherit the environment variables of the shell used to start “supervisord” except for the ones overridden here.

Fixes #571
Fixes #519

/cc @inbeom, @ddollar

[stephenyeargin]

In browsing through branches, I see this as another possible approach.

https://github.com/doitian/foreman/commit/36f0ae4e57e962318e0b4ebb646622f7cec86253

[ddollar]

Thanks!