Capture ValueError along with ImportError

For issue #168
It appears the new relative imports I was using was throwing an
unexpected error in ST2 and breaking.

In the future I should probably not use Error handling for flow control
like this and just determin the ST version and then use the appropriate
import method.

git_gutter.py

@@ -3,7 +3,7 @@
 import sublime_plugin
 try:
     from .view_collection import ViewCollection
-except ImportError:
+except (ImportError, ValueError):
     from view_collection import ViewCollection
 
 

git_gutter_change.py

@@ -2,7 +2,7 @@
 import sublime_plugin
 try:
     from .view_collection import ViewCollection
-except ImportError:
+except (ImportError, ValueError):
     from view_collection import ViewCollection
 
 

git_gutter_handler.py

@@ -7,7 +7,7 @@
 try:
     from . import git_helper
     from .view_collection import ViewCollection
-except ImportError:
+except (ImportError, ValueError):
     import git_helper
     from view_collection import ViewCollection
 

view_collection.py

@@ -13,8 +13,8 @@ class ViewCollection:
     def add(view):
         key = ViewCollection.get_key(view)
         try:
-            from GitGutter.git_gutter_handler import GitGutterHandler
-        except ImportError:
+            from .git_gutter_handler import GitGutterHandler
+        except (ImportError, ValueError):
             from git_gutter_handler import GitGutterHandler
         handler = ViewCollection.views[key] = GitGutterHandler(view)
         handler.reset()