Added Solution Explorer to the important scopes

In Visual Studio 2013 several conflicting key bindings were added to the
"Solution Explorer" key binding scope.  Previously VsVim had only been
searching the "Global" and "Text Editor" scopes.  Adding this new scope
allowed us to find and remove the new conflicting key bindings

closes #1193
CommandKeyBinding not equatable
Removed duplicate entries from conflicting key dialog

Visual Studio often associates several key strokes with a single
command.  If multiple of the key strokes conflicted with VsVim then the
command would be listed multiple times in the dialog when the "Visual
Studio" drop down was clicked.  This changes it to only list unique
names
Better removal of key bindings

Unfortunately commands like SolutionExplorer.OpenFileFilters just don't
want to relinquish their key bindings.  You have to ask them to remove
the key bindings twice else it will only remove part of them.  So
frustrating

Related to #1193