Fix dynamic-login with grub2

Grub2 messes up arguments with double quotes in them, changing from
key="value" to "key=value" [1]. Support this format as well.

[1] https://bugzilla.redhat.com/show_bug.cgi?id=950760

Change-Id: Icf4c9f86009d29a342d6e0e21644af680066b0b2

diskimage_builder/elements/dynamic-login/static/usr/local/bin/dynamic-login

@@ -19,14 +19,14 @@ set -o pipefail
 
 # Reads an encrypted root password from the kernel command line and set
 # it to the root user
-if [[ $(</proc/cmdline) =~ rootpwd=\"([^\"]+)\" ]]; then
+if [[ $(</proc/cmdline) =~ rootpwd=\"?([^\"]+)\" ]]; then
     echo "root:${BASH_REMATCH[1]}" | chpasswd -e
 fi
 
 # Reads a sshkey from the kernel command line and appends it to the root
 # user authorized_keys
 SSHDIR=/root/.ssh
-if [[ $(</proc/cmdline) =~ sshkey=\"([^\"]+)\" ]]; then
+if [[ $(</proc/cmdline) =~ sshkey=\"?([^\"]+)\" ]]; then
     mkdir -p $SSHDIR
     chmod 700 $SSHDIR
     echo "${BASH_REMATCH[1]}" > $SSHDIR/authorized_keys