OSX Pip and Python versions off

**1. Please specify the following:**
- OS: OS X
- Shell: Bash

- [x] **I have reviewed the troubleshooting tips described [here]() and they do not solve my problem**

**2. Description**
Not sure the best way to report this, as I patched my way through it.

During step 6 of the installer, I ran into the following issue:


The `python_installer` was looking for a `pip` binary, when only `pip3` and `pip3.7` existed

Patching the references on `python_installer` line 154 (and docstring on 198) to use `pip3` instead of `pip` resolves the issue.

This happened again in the bundled_installer, when it was looking for `python` instead of `python3.7`, so I patched the file paths inside `bundled_installer` `install_ebcli` to use `python3.7`

With these changes my install worked fine and I've successfully used the eb cli since.

Start with step 6 of the installer, especially python_installer line 154 and its docstring at line 198, then inspect bundled_installer and install_ebcli. Reproduce the OS X installation issue and verify that systems providing pip3 and python3.7 complete installation without manual patching.

Written by the indexing model from the issue text.