[Bugfix:Plagiarism] Create Lichen directory during install (#90)

Author: williamjallen

install_lichen.sh

@@ -12,6 +12,8 @@ lichen_repository_dir=/usr/local/submitty/GIT_CHECKOUT/Lichen
 lichen_installation_dir=/usr/local/submitty/Lichen
 lichen_vendor_dir=/usr/local/submitty/Lichen/vendor
 
+rm -rf "$lichen_installation_dir"
+mkdir "$lichen_installation_dir"
 cp -r "$lichen_repository_dir"/* "$lichen_installation_dir"
 
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