Add IFM (#1104)

* Add IFM

* Modified IFM

added source code link

* Add IFM

* add missing dot after description
* remove redundant source code link

README.md

@@ -639,6 +639,7 @@ See https://github.com/n1trux/awesome-sysadmin#distributed-filesystems
   * [eXtplorer](https://extplorer.net/) - A PHP and Javascript based File Manager. ([Source Code](https://extplorer.net/projects/extplorer/repository)) `MPLv1.1/GPLv2` `PHP`
   * [goBrowser](https://github.com/xataz/gobrowser) - Simple http file browser. ([Source Code](https://github.com/xataz/gobrowser)) `GPLv3` `Go`
   * [h5ai](https://larsjung.de/h5ai/) - Modern file indexer for HTTP web servers with focus on your files. Directories are displayed in a appealing way and browsing them is enhanced by different views, a breadcrumb and a tree overview. ([Demo](https://larsjung.de/h5ai/demo/), [Source Code](https://github.com/lrsjng/h5ai)) `MIT` `PHP`
+  * [IFM](https://github.com/misterunknown/ifm/) - A single script file manager. `MIT` `PHP`
   * [Monsta FTP](http://www.monstaftp.com/) - Open source PHP/Ajax cloudware that puts FTP file management right in your browser, anywhere, any time. ([Demo](http://mftp.live/), [Source Code](https://github.com/MonstaApps/Monsta-FTP)) `GPLv3` `PHP`
   * [ResourceSpace](http://www.resourcespace.org) - ResourceSpace open source digital asset management software is the simple, fast, & free way to organise your digital assets. ([Demo](http://www.resourcespace.org/trial), [Source Code](http://www.resourcespace.org/svn)) `BSD/Other` `PHP`
   * [Sprut.io](https://sprut.io) - 2 panel file manager with drag and drop features, code editor, text search, hotkeys. ([Demo](https://demo.sprut.io:9443), [Source Code](https://github.com/LTD-Beget/sprutio)) `GPLv3` `Python`