Allow options in command, add travis integration, and update readme

[almasaeed2010]

Hello,

This pull request adds travis CI integration to tripal_install. To make this possible we had to refactor the code to accept a non-interactive mode where all the options are passed through the cli.

However, since we don't own the repo we couldn't validate the travis yaml file. But that should automatically happens once you enable travis on your end before merging this pull request. From there, we can update the code until it passes then merge.

Please let me know if you have any questions.

Thanks!

[almasaeed2010]

Running the tests yields that this works with php 7.0, 7.1 but not 7.2

[shawnawsu]

I am so sorry I didn't see this till now, I was apparently not watching this repo.

This pull request troubles me. I understand the desire to test it with travis but it adds a lot of additional code that doesn't speak to performing the required tasks and seems overcomplicated, and far from the ideal of maintaining simplicity of code.

@spficklin, thoughts?

[spficklin]

@shawnawsu I think we should merge this in as we do need some travis CI integration.