Add contitional update package repositories to install_package()

This helps us ensure that we update the repositories only the first time
we need to install packages

Rebased and incorporated into install_package()

Change-Id: Id987aa7742f5d6807bc97eb6784cf18557c919d2
diff --git a/functions b/functions
index c109eae..8ed9960 100644
--- a/functions
+++ b/functions
@@ -536,7 +536,11 @@
     if [[ -z "$os_PACKAGE" ]]; then
         GetOSVersion
     fi
+
     if [[ "$os_PACKAGE" = "deb" ]]; then
+        [[ "$NO_UPDATE_REPOS" = "True" ]] || apt_get update
+        NO_UPDATE_REPOS=True
+
         apt_get install "$@"
     else
         yum_install "$@"
diff --git a/stack.sh b/stack.sh
index 80ea271..90d8c62 100755
--- a/stack.sh
+++ b/stack.sh
@@ -183,7 +183,7 @@
 
     # Give the non-root user the ability to run as **root** via ``sudo``
     if [[ "$os_PACKAGE" = "deb" ]]; then
-        dpkg -l sudo || apt_get update && install_package sudo
+        dpkg -l sudo || install_package sudo
     else
         rpm -qa | grep sudo || install_package sudo
     fi
@@ -654,7 +654,6 @@
 
 # Install package requirements
 if [[ "$os_PACKAGE" = "deb" ]]; then
-    apt_get update
     install_package $(get_packages $FILES/apts)
 else
     install_package $(get_packages $FILES/rpms)