Include apt-get install yum-utils during installation for Ubuntu

This is required to allow yum-based bootstraping of definition files.
e.g., CentOS-based containers. Note, however, there are currently no deb
packages for yum or yum-utils in the standard Ubuntu 20.04 LTS (focal)
repositories. An alternative approach to installing either yum and/or
dnf will be required in the future.

Also fixed a typo of a missing colon on a call to the log::error
function when naked-singularity.sh checks for a pre-existing
installation of Singularity.

README.md

@@ -57,8 +57,8 @@ University of California, San Diego
 
 ## Version
 
-1.7.2
+1.7.4
 
 ## Last Updated
 
-Sunday, June 20th, 2021
+Thursday, July 22nd, 2021

naked-singularity.sh

@@ -17,7 +17,7 @@
 #
 # LAST UPDATED
 #
-#   Wednesday, June 16th, 2021
+#   Thursday, July 22nd, 2021
 #
 # ----------------------------------------------------------------------
 
@@ -75,7 +75,7 @@ naked::install() {
   log::output 'Checking if Singularity is already installed ...'
   singularity --version > /dev/null 2>&1
   if [[ "${?}" -eq 0 ]]; then
-    log:error "Singularity is installed: $(singularity --version)"
+    log::error "Singularity is installed: $(singularity --version)"
     return 1
   else
     log::output 'Singularity is not installed.'
@@ -152,6 +152,7 @@ naked::install() {
     apt-get -y install git
     apt-get -y install cryptsetup-bin
     apt-get -y install debootstrap
+    apt-get -y install yum-utils
 
   else