Updating to base off of 'python:2.7.14-alpine3.6' instead of just 'alpine:3.6'

[bdlamprecht]

This is an update to both ansible-silo-base and ansible-silo. I was having really weird issues getting the --bundle to work with certain python libraries as were described in issues #53 and #54. Some minor enhancements that I made were the following:

1. Due to the complexity of the command for installing the created bundle, several instructional lines were added to the build script so the user could easily copy / paste after the script ran.
2. Similar to 1 above, I added the same type of lines to the Makefile for ansible-silo.
3. Added a few additional libraries that I thought would be worthwhile for others such as bcrypt and napalm (for managing networking devices). That last requirement necessitated leaving pkgconf, libxml2, and libxslt around to connect to Juniper devices via junos-eznc. The additional space for this in ansible-silo-base is only an additional 29% (155MB for 2.0.1 and 201MB for 3.0.0). This size could be reduced further, but didn't want to spend time optimizing for diminishing returns unless it was a real issue.
4. Added the option to install custom python libraries in the bundle if there was a requirements.txt file in the
5. Probably something else, but don't recall at the moment.

This builds and runs just fine for me, but as you know Alpine Linux likes to not keep their libraries around for very long once a new version is released, so time is of the essence to get this merged if you approve of the changes.

[bdlamprecht]

@udondan It looks like there might be a problem with your .travis.yml file when trying to install bats (0.4.0-1.1). Not sure how I can help resolve this issue.

[bdlamprecht]

Yeah, I don't really care about getting credit, I just had to make the changes I did to get the silo working for my project. I can resolve all of the issues which you brought up, but since it:

1. Has been so long and most likely all of the packages have once again been changed
2. Is your project which I just "commandeered" for my use

and

3. You know the intricacies of what you had working more so than me

Why don't you go ahead and make the changes you'd like. Let me know when I can cancel this PR. Also, I'd be happy to help you test your version of the ansible-silo 3.0.0 release.

Does that work for you?

[udondan]

Hi Brady,

sure, I'll take care of that. I'll make sure to switch to the python-alpine image and add the packages of your PR.

Thanks, Daniel