Don't assume that profiles for index.php are from webgrind itself

[kasparsd]

Fixes #130.

• Webgrind is a generic tool to display Xdebug profiling results. It works by parsing all /tmp/cachegrind.out* files.
• It currently assumes that all profiling results for index.php are from Webgrind itself. That is a generic assumption and doesn't apply in any of the Docker use-cases where the Webgrind container is attached to the /tmp directory of other PHP containers.

Solutions:

• Default to showing all profiling results.
• Alternative: offer an environment variable or some other configuration option to adjust this particular behaviour.