removing _1 suffix

coming from #342,
this will change container naming to avoid the `_1` suffix, the change will be:
```
container_1 => container
container_2 => container_2
container_3 => container_3
...
```
I updated all docs I found to reflect this. test

Signed-off-by: Benjamin Eidelman <beneidel@gmail.com>
Off-topic for this PR, but we should really change these docs to the much cleaner:

    fig run db /bin/sh -c "psql -h db -U docker"

Also, the /bin/sh -c in this is redundant.