Udpated plum.txt

* Filled in the blank in plum.txt, added plum
Updated tree.txt

* Updated text in tree.txt, added tree
Added grape.txt
Added firetruck.txt

* New file with firetruck symbol picture and text
Added yellow directory

* Created empty yellow directory
* Added file .keep to commit directory
Renamed hiding turtle

* Renamed hiding turtle to turtle
* Removed ., made file visible
Challenge 3 and 4 Items

* Moved/renamed turtle, ruby and school bus to color directories
* Removed unsorted directory
* Deleted .html vandal files