Revert "Add bufexplorer's configs"

This reverts commit 2a3df1cb69d614a8ad51451fa9c76c64040a1d1b.
Revert "Vim: Plug-in: BufExplorer"

This reverts commit e7b1ac68fd4c46c6bee77b8a81dad442f6a2c093.
Vim: Plug-in: Buffergator
Add Buffergator's config