Purge package lists to reduce image size (fixes #34)

[mattva01]

This may increase build times (unless the two apt-get blocks are merged), but it should significantly reduce the end image size.

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[ahmetb]

@Eilon for some reason PR is not built with CI? Can you please check CircleCI still appears in repo settings?

@mattva01 how much does this actually reduce the image size? can you please provide a before/after comparison?

[mattva01]

@ahmetalpbalkan It's weird, it only saves around 20 megs. it should be more
mattva01/aspnet latest 4cda43d5195b 32 minutes ago 460.2 MB
microsoft/aspnet latest 6d21a65194aa 39 hours ago 479.4 MB

It's still a good practice though, especially since images are designed to inherit from it.

[mattva01]

Oh, it's because upstream is debian I think and not a more bare repo.

Also, if you do want to merge this, I should probably remove the "-qq" from the first "apt-get update". It passes the tests on my circleci(https://circleci.com/gh/mattva01/aspnet-docker/1), but probably better to have that be verbose for debugging purposes.

[ahmetb]

@mattva01 I think we are just fine as is. We will be transitioning to official .NET implementation soon and mono will go away. I expect package size to decrease a lot and I prefer simplicity in Dockerfile for 20 MB. 😄 Thanks, though.

[mattva01]

Haha, no problem. Do remember this trick for your future builds though. A lot of folks forget about it and in some cases it can save hundreds of megs.

[Eilon]

@ahmetalpbalkan I just enabled the feature to auto-build PRs from forks.

[ahmetb]

@Eilon ah thanks, I forgot to mention that.