Use use_tabs_not_buffers=0 by default

Ref: https://github.com/davidhalter/jedi-vim/issues/408#issuecomment-101997691

README.rst

@@ -120,12 +120,11 @@ are automatically initialized, but you can skip this:
     let g:jedi#auto_vim_configuration = 0
 
 
-If you are a person who likes to use VIM-buffers not tabs, you might want to
-put that in your ``.vimrc``:
+You can make jedi-vim use tabs when going to a definition etc:
 
 .. code-block:: vim
 
-    let g:jedi#use_tabs_not_buffers = 0
+    let g:jedi#use_tabs_not_buffers = 1
 
 If you are a person who likes to use VIM-splits, you might want to put this in your ``.vimrc``:
 

autoload/jedi.vim

@@ -12,7 +12,7 @@ let s:deprecations = {
 \ }
 
 let s:default_settings = {
-    \ 'use_tabs_not_buffers': 1,
+    \ 'use_tabs_not_buffers': 0,
     \ 'use_splits_not_buffers': 1,
     \ 'auto_initialization': 1,
     \ 'auto_vim_configuration': 1,

doc/jedi-vim.txt

@@ -423,12 +423,12 @@ manually by calling a function in your configuration file: >
 ------------------------------------------------------------------------------
 6.7. `g:jedi#use_tabs_not_buffers`	*g:jedi#use_tabs_not_buffers*
 
-By default, jedi-vim opens a new tab if you use the "go to", "show
-definition", or "related names" commands. When you set this option to 0, they
-open in the current buffer instead.
+You can make jedi-vim open a new tab if you use the "go to", "show
+definition", or "related names" commands. When you leave this at the default
+(0), they open in the current buffer instead.
 
 Options: 0 or 1
-Default: 1 (Command output is put in a new tab)
+Default: 0 (Command output is put in a new tab)
 
 ------------------------------------------------------------------------------
 6.8. `g:jedi#squelch_py_warning`	*g:jedi#squelch_py_warning*

test/goto.vim

@@ -48,6 +48,7 @@ end
 describe 'goto_with_tabs'
     before
         set filetype=python
+        let g:jedi#use_tabs_not_buffers = 1
     end
 
     after

test/pyimport.vim

@@ -2,6 +2,10 @@ source plugin/jedi.vim
 source test/utils.vim
 
 describe 'pyimport'
+    before
+        let g:jedi#use_tabs_not_buffers = 1
+    end
+
     after
         bd!
         bd!