Should use environment component of SECTION_IO_API_ENDPOINT when proxy component is missing

[jstangroome]

varnish-cli-bridge always extracts the account ID and application ID from the provided SECTION_IO_API_ENDPOINT value. However, it only extracts the environment from the URL if the proxy name is also in the URL.

For example:
https://aperture.section.io/api/v1/account/1/application/2/environment/Staging

Is incorrectly interpreted as:

• account 1
• application 2
• environment Production

But this example:
https://aperture.section.io/api/v1/account/1/application/2/environment/Staging/proxy/varnish

Is correctly interpreted as:

• account 1
• application 2
• environment Staging