Test command versions are the expected ones on images

[humitos]

It happened that conda command was not found in some of the images deployed, or the pip / virtualenv version was not the one that we expected and other similar issues.

It would be good if we can have a script that spins up the docker image and execute all of these commands and compare the versions returned by each command on Travis after it builds the image.

Some ideas we can use to compare:

• python2 --version == Python 2.7.18
• conda --version == conda 4.6.14
• cargo --version == cargo 1.46.0 (149022b1d 2020-07-17)
• ubuntu version
• virtualenv
• pip in all python versions installed
• etc

Related to #53