fix java search for method implementors to search for declarations

jdt search for methods doesn't support implementors, so use declarations
instead.

refs #251
prevent possible error if htmldjango syntax is loaded before the ftplugin

fixes #256
update python doc index to fix typo + clarify some common questions

refs #204
fix osx url open command to quote the url arg

refs #249
Python validator: check g:loaded_syntastic_plugin

The pyflakes plugin apparently was generalized into the syntastic
plugin. This adds a check to detect it.