Configuration: these are the defaults:
let g:local_vimrc = {'names':['.vimrc'],'hash_fun':'LVRHashOfFile'}

Features:
- When Vim starts up, every directory from root to the directory of the file
  is traversed and special files such as .(local-)vimrc files are sourced

- Because you don't want to run untrusted code by accident, this plugin
  calculates a hash before sourcing. If its unknown you must confirm sourcing
  the file. The hash is updated automatically if you write a local vimrc file.

USAGE:
========
create a .vimrc in your project directory.
To make sure it's working, add: echo "this file is being soucred by vim"

Sample local .vimrc
===================

augroup LOCAL_SETUP
  " using vim-addon-sql providing alias aware SQL completion for .sql files and PHP:
  autocmd BufRead,BufNewFile *.sql,*.php call vim_addon_sql#Connect('mysql',{'database':'DATABASE', 'user':'USER', 'password' : 'PASSWORD'})

  " for php use tab as indentation character. Display a tab as 4 spaces:
  " autocmd BufRead,BufNewFile *.php set noexpandtab| set tabstop=4 | set sw=4
  autocmd FileType php setlocal noexpandtab| setlocal tabstop=4 | setlocal sw=4

  " hint: for indentation settings modelines can be an alternative as well as
  " various plugins trying to set vim's indentation based on file contents.
augroup end


KISS: If you need filetype support write au commands into the local vimrc.

Yes I know that there are already a couple of existing similar plugins.
But I they work for filetypes only (why?) and they don't verify file contents.


Alternatives
============
directory local .vimrc without walking up directory tree using vim builtin 'exrc' option:
  :h 'exrc'
  :h 'secure'
but 'secure' is not very secure, eg echo system('cat .vimrc') is executed
unless the file belongs to a different owner..