Rewrite bootstrapper in Python

- This was going to get too complex for bash. Only way to
  kill those scripts is before they get too complex.
- Better progress messages from bootstrapper.
- Differentiate between bootstrapper & installer
- Cleanup documentation a little bit

docs/guides/install.rst

@@ -10,7 +10,7 @@ The quick way to install The Littlest JupyterHub (tljh) is:
 
 .. code-block:: bash
 
-   curl https://raw.githubusercontent.com/yuvipanda/the-littlest-jupyterhub/master/installer/install.bash | sudo bash -
+   curl https://raw.githubusercontent.com/yuvipanda/the-littlest-jupyterhub/master/bootstrap/bootstrap.py | sudo python3 -
 
 This takes 2-5 minutes to run. When completed, you can access your new JupyterHub
 at the public IP of your server!
@@ -21,7 +21,7 @@ after installation.
 Slightly less quick installation
 --------------------------------
 
-If you can read ``bash`` and are nervous about the previous installation method,
+If you can read ``python3`` and are nervous about the previous installation method,
 you can inspect the installer script before running it.
 
 
@@ -29,7 +29,7 @@ you can inspect the installer script before running it.
 
    .. code-block:: bash
 
-      curl https://raw.githubusercontent.com/yuvipanda/the-littlest-jupyterhub/master/installer/install.bash  -o install.bash
+      curl https://raw.githubusercontent.com/yuvipanda/the-littlest-jupyterhub/master/bootstrap/bootstrap.py -o bootstrap.py
 
 2. Read the install script source using your favorite text editor
 
@@ -37,6 +37,6 @@ you can inspect the installer script before running it.
 
    .. code-block:: bash
 
-      sudo install.bash
+      sudo python3 bootstrap.py
 
    This should have the exact same effects as the quick installer method.