fix: erratic initialization of tags

Short version
-------------

phpcomplete#GetCurrentNameSpace(file_lines) returns a Dictionary
of duplicate values with different keys (one for each import)
to the main  phpcomplete#CompletePHP(findstart, base) function.

The author of the original code forgot to unsed the
'no_namespace_candidate' tag for each (tag in imports) iterations.

Details
-------

The values from 'no_namespace_candidate' were assignet do
all keys in the 'imports' dictionary.

This is a huge bug because if a .php file specified more
than one 'use dependency', they would all point to the file
and methods of the -last- use dependency.

I have reproduced the error in the tarball below. Try switching
the order of the two use statements and see what happens.

This is on a non-patched ctags.

list of software:

    $ exuberant-ctags --version
    Exuberant Ctags 5.8, Copyright (C) 1996-2009 Darren Hiebert
      Compiled: Nov 15 2011, 20:02:35
      Addresses: <dhiebert@users.sourceforge.net>, http://ctags.sourceforge.net
      Optional compiled features: +wildcards, +regex

    $ gvim --version
    VIM - Vi IMproved 7.4 (2013 Aug 10, compiled Sep 27 2014 14:49:31)
    Included patches: 1-417
    Modified by Gentoo-7.4.417

Tarball (demonstrates bug)
--------------------------
$ tar -cv -f- project-complete/ | gzip  | base64
project-complete/
project-complete/Zumba.php
project-complete/autoload/
project-complete/autoload/autoload.php
project-complete/autoload/autoload.sh
project-complete/php.ctags
project-complete/make.php.ctags
project-complete/Do.php
project-complete/Group/
project-complete/Group/Task.php
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