Reduce the size of the image

Current image is about **700 MB**, these changes reduce it to **460 MB**.
Some of these have no effect.  Also, what if someone wants to use this as a base to a development environment and needs access to the man pages or docs?  I think that if the sliming is to get a smaller production footprint, it would be better to go the route of our `slim` versions (discussed [here](https://github.com/docker-library/python/issues/16), [here](https://github.com/docker-library/docs/issues/43), and [here](https://github.com/docker-library/node/pull/19)).

Current `buildpack-deps`:
```console
$ docker run -it --rm buildpack-deps:latest
root@c27eab62b164:/# du -hs /tmp/             
0	/tmp/
root@c27eab62b164:/# du -hs /var/tmp/
0	/var/tmp/
root@c27eab62b164:/# du -hs usr/share/man
33M	usr/share/man
root@c27eab62b164:/# du -hs usr/share/info
1.2M	usr/share/info
root@c27eab62b164:/# du -hs /var/cache/man/
du: cannot access '/var/cache/man/': No such file or directory
root@c27eab62b164:/# du -hs /var/cache/apt/
0	/var/cache/apt/
root@c27eab62b164:/# du -hs /usr/share/doc/ 
95M	/usr/share/doc/
root@c27eab62b164:/# du -hs /usr/share/locale
90M	/usr/share/locale
```

debian:
```console
$ docker run -it --rm debian
root@d221657dde29:/# du -hs /tmp/             
0	/tmp/
root@d221657dde29:/# du -hs /var/tmp/
0	/var/tmp/
root@d221657dde29:/# du -hs usr/share/man
5.1M	usr/share/man
root@d221657dde29:/# du -hs usr/share/info
476K	usr/share/info
root@d221657dde29:/# du -hs var/cache/man
du: cannot access `var/cache/man': No such file or directory
root@d221657dde29:/# du -hs /var/cache/apt/
0	/var/cache/apt/
root@d221657dde29:/# du -hs /usr/share/doc/ 
6.9M	/usr/share/doc/
root@d221657dde29:/# du -hs /usr/share/locale
29M	/usr/share/locale
```