my neosnipet setting via "http://kazuph.hateblo.jp/entry/2013/01/19/193745"
" <TAB>: completion.
" inoremap <expr><TAB> pumvisible() ? "\<C-n>" : "\<TAB>"
inoremap <expr><S-TAB> pumvisible() ? "\<C-p>" : "\<S-TAB>"
" Plugin key-mappings.
imap <C-;> <Plug>(neosnippet_expand_or_jump)
smap <C-;> <Plug>(neosnippet_expand_or_jump)
" SuperTab like snippets behavior.
" imap <expr><TAB> neosnippet#jumpable() ? "\<Plug>(neosnippet_expand_or_jump)" : pumvisible() ? "\<C-n>" : "\<TAB>"
imap <expr><TAB> pumvisible() ? "\<C-n>" : neosnippet#jumpable() ? "\<Plug>(neosnippet_expand_or_jump)" : "\<TAB>"
smap <expr><TAB> neosnippet#jumpable() ? "\<Plug>(neosnippet_expand_or_jump)" : "\<TAB>"
" For snippet_complete marker.
if has('conceal')
set conceallevel=2 concealcursor=i
endif