Sync master to dev. (#102)

* More robust checking of age of apt cache (#90)

* Don't install apt-fast from source (#96)

* Clean cache directory after use (#95)

* Only install apt-fast from source if not present (#97)

* Revert "Don't install apt-fast from source (#96)"

This reverts commit 854bb53.

* Only install apt-fast from source if not present

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Co-authored-by: John Hughes <[email protected]>
Co-authored-by: Pascal Roeleven <[email protected]>