Bug 7804 - Add Koha Plugin System

Bug 7804 - Add Koha Plugin System

Adds support for custom plugins. At the moment the Plugins
feature supports two types of plugins, reports and tools.

Plugins are installed by uploading KPZ ( Koha Plugin Zip )
packages. A KPZ file is just a zip file containing the
perl files, template files, and any other files neccessary
to make the plugin work.

Test plan:
1) Apply patch
2) Run updatedatabase.pl
3) Create the directory /var/lib/koha/plugins
4) Add the lines
      <pluginsdir>/var/lib/koha/plugins</pluginsdir>
      <enable_plugins>1</enable_plugins>"
   to your koha-conf.xml file
5) Add the line
       Alias /plugin/ "/var/lib/koha/plugins/"
   to your koha-httpd.conf file
6) Restart your webserver
7) Access the plugins system from the "More" pulldown
8) Upload the example plugin file provided here
9) Try it out!

Signed-off-by: Bernardo Gonzalez Kriegel <bgkriegel@gmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Jared Camins-Esakov <jcamins@cpbibliography.com>