Configuration edits

When I installed OGV, it din't show any models. In a quick inspection I found out that the path to mged and obj were hard coded in the config file, which were different than what I had on my machine. It din't gave much of an error, except a half gibberish looking error on ```model_display.php``` and there was definitely no cue on how to solve this for the user.

Also, in to do list there was a desire to have users edit configuration file from the browser itself. So I added 
* ```config-edit.php``` and ```config-process.php``` that will create the ```config.php``` file itself and if it's unable to create file then it will give a simple copy paste solution to user.
* ```config-validate.php``` that will validate the variables whose validity is crucial for the whole app, thus giving an error notification on each page to correct the errors. (Just like we have update notifications in wordpress).

I have edited ```upload.php```, so that we can get error notification there too, and then edit stylesheet to give styles to the form that edits configuration and error messages.

I also had to (with heavy heart) add an inline style in ```config-edit.php``` , because body was ```overflow:hidden``` in the original styles, changing that would have made a mess to other pages and we have no classes for the body so I had to add a ```overflow:auto``` inline overriding the styles in style.css. I will keep the larger task of code clean up and CSS clean up for another pull request. 

Then I have removed ```env``` from $mgedPath, as it's not the path to mged, and as currently the path is entered by user, so it may be confusing if we make user add env. I have concatenated ```env``` to ```$cmd```