Use dependency_links to install prompt_toolkit 2.0

To avoid having to install using a bash script, we can specify a version of prompt_toolkit and provide the github branch tarball for 2.0 as a dependency link.

This means when installing with pip install sml-sync --process-dependency-links, pip will install prompt toolkit from the github repo.

This means we can close the bitbucket repo.

setup.py

@@ -16,14 +16,17 @@
     entry_points={
         'console_scripts': ['sml-sync=sml_sync:run']
     },
+    # prompt_toolkit 2.0 is currently only available from github:
+    dependency_links = ['https://github.com/'
+                        + 'jonathanslenders/python-prompt-toolkit/'
+                        + 'tarball/2.0#egg=prompt_toolkit-2.0'],
     install_requires=[
         'sml',
         'daiquiri',
         'paramiko',
         'inflect',
         'watchdog',
-        'semantic_version'
-        # This is currently missing prompt-toolkit
-        # (waiting for 2.0 to be released)
+        'semantic_version',
+        'prompt_toolkit>=2.0'
     ]
 )