check python and pip versions (#19)

Author: DomAmato

install.sh

@@ -61,7 +61,8 @@ function install_software() {
 }
 
 function check_python_version() {
-    if ! python3 -V | grep '3.[7-9].[0-9]' > /dev/null 2>&1; then
+    python3 -V | grep '3.[7-9].[0-9]' &> /dev/null
+    if ! [ $? == 0 ]; then
         echo "An unsupported version of python 3 is installed. Must have python 3.7+ installed to use the Hologram SDK"
         exit 1
     fi
@@ -124,7 +125,8 @@ do
             pause "Installing $program. Press [Enter] key to continue...";
             install_software 'python3-pip'
         fi
-        if ! pip3 -V | grep '3.[7-9]' >/dev/null 2>&1; then
+        pip3 -V | grep '3.[7-9]' &> /dev/null
+        if ! [ $? == 0 ]; then
             echo "pip3 is installed for an unsupported version of python."
             exit 1
         fi