use gimme_pkg helper in a few more gimmes

gimmes/rstudio

@@ -10,7 +10,7 @@ gimme basictex
 
 if [[ "$OS" = "Darwin" ]]; then
 	if ! [[ -d "$HOME/Applications/RStudio.app/" ]]; then
-		brew cask install rstudio
+		gimme_pkg rstudio
 		# Make things a bit easier for RStudio...
 		sudo ln -s "$(brew --prefix)/bin/R" "/usr/local/bin/R"
 	fi

gimmes/sourcetree

@@ -1,7 +1,7 @@
 #!/bin/bash
 set -o errexit -o pipefail
 if [[ "$OS" = "Darwin" ]]; then
-	brew cask install sourcetree
+	gimme_pkg sourcetree
 else
 	echo "WARN: no equivalent for when OS=$OS"
 fi

gimmes/wireshark

@@ -1,10 +0,0 @@
-#!/bin/bash
-set -o errexit -o pipefail
-
-if ! has wireshark; then
-	if [[ "$OS" = "Darwin" ]]; then
-		brew cask install wireshark
-	else
-		gimme_pkg wireshark
-	fi
-fi