added 5th parameter to fetchparam(path... IOT prevent force to lower case

Was having issues with my live server not finding images that had capital letters in their titles (it worked locally though). Without the fifth parameter, the default value of $force_lower is true, causing all image paths to be converted to lower case. See old Statamic discussion [here](http://support.statamic.com/discussions/problems/2917-this-getparam-returns-the-value-in-lower-case).