Remove pycodestyle plugin's dependency on autopep8 (#813)

pyls/plugins/pycodestyle_lint.py

@@ -1,15 +1,19 @@
 # Copyright 2017 Palantir Technologies, Inc.
 import logging
 import pycodestyle
-from autopep8 import continued_indentation as autopep8_c_i
 from pyls import hookimpl, lsp
 
-# Check if autopep8's continued_indentation implementation
-# is overriding pycodestyle's and if so, re-register
-# the check using pycodestyle's implementation as expected
-if autopep8_c_i in pycodestyle._checks['logical_line']:
-    del pycodestyle._checks['logical_line'][autopep8_c_i]
-    pycodestyle.register_check(pycodestyle.continued_indentation)
+try:
+    from autopep8 import continued_indentation as autopep8_c_i
+except ImportError:
+    pass
+else:
+    # Check if autopep8's continued_indentation implementation
+    # is overriding pycodestyle's and if so, re-register
+    # the check using pycodestyle's implementation as expected
+    if autopep8_c_i in pycodestyle._checks['logical_line']:
+        del pycodestyle._checks['logical_line'][autopep8_c_i]
+        pycodestyle.register_check(pycodestyle.continued_indentation)
 
 log = logging.getLogger(__name__)