Fix sparkup binding interfering with typing

With leader now as space, and Sparkup operating in insert mode, it becomes
impossible to type things like "do not" (space and 'n').

vim/settings/sparkup.vim

@@ -1,2 +0,0 @@
-"g:sparkupExecuteMapping (Default: '<C-e>') - Mapping used to execute sparkup.
-let g:sparkupNextMapping = '<Leader>n'