Do not install one more curl into image

[dmitry-j-mikhin]

Otherwise there will be 2 curls inside image:

• /usr/bin/curl (from deb pkg)
• /usr/local/bin/curl (compiled one)

We need only ca-certificates for /usr/local/bin/curl, so it can check certificates validity.

Also clean apt cache to reduce image size.

[yurymuski]

great, thank you =)

I will check and release new version on a weekend

[dmitry-j-mikhin]

Super, also thank you for this great repo!