Refactor cache dir behaviour

[rlenferink]

Currently the celix .cache dir is default created in the workdir and not cleanup during shutdown. To make celix act more like a normal program this should be refactored.

Move the default location of the cache file to (e.g.) /tmp/celix/cache-XXXXXXX (using mktemp) and default cleanup the .cache during shutdown.

Ensure that the cache behavior is configurable to that user can opt-in to the previous behavior.

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Original creation date: 09/Apr/2018 Reporter: @pnoltes