title: crash error when execute docker-compose
body: <p>I executed the command</p>
  
  <pre><code>docker-compose down
  </code></pre>
  
  <p>and get this error</p>
  
  <pre><code>Traceback (most recent call last):
  File "bin/docker-compose", line 3, in &lt;module&gt;
  File "compose/cli/main.py", line 68, in main
  File "compose/cli/main.py", line 115, in perform_command
  File "compose/cli/command.py", line 37, in project_from_options
  File "compose/cli/command.py", line 91, in get_project
  File "compose/config/config.py", line 362, in load
  File "compose/config/config.py", line 528, in process_config_file
  File "compose/config/validation.py", line 378, in 
  validate_against_config_schema
  File "compose/config/validation.py", line 439, in handle_errors
  File "compose/config/validation.py", line 439, in &lt;genexpr&gt;
  File "compose/config/validation.py", line 365, in 
  process_config_schema_errors
  File "compose/config/validation.py", line 237, in handle_generic_error
  File "compose/config/validation.py", line 305, in 
  _parse_oneof_validator
  File "compose/config/validation.py", line 320, in 
  _parse_oneof_validator
  File "compose/config/validation.py", line 285, in 
  _parse_valid_types_from_validator
   File "compose/config/validation.py", line 201, in anglicize_json_type
  e
  AttributeError: 'bool' object has no attribute 'startswith'
  Failed to execute script docker-compose
  </code></pre>
  
  <p>I don't know what happened, everything was ok yesterday then just goes wrong today without any reasons.</p>
  
  <pre><code>Docker version 17.06.0-ce, build 02c1d87
  docker-compose version 1.14.0, build c7bdf9
  </code></pre>