kea: update package to 1.8.0

Update kea to the latest stable version (1.8.0) and add kea-shell 
package.

Signed-off-by: Tiago Gaspar <tiagogaspar8@gmail.com>

net/kea/patches/004-replace-rev-with-awk.patch

@@ -0,0 +1,11 @@
+--- a/src/bin/keactrl/keactrl.in
++++ b/src/bin/keactrl/keactrl.in
+@@ -98,7 +98,7 @@ get_pid_from_file() {
+     # Extract the name portion (from last slash to last dot) of the config file name
+     # File name and extension are documented in src/lib/util/filename.h
+     local conf_name
+-    conf_name=$(basename -- "${kea_config_file}" | rev | cut -f2- -d'.' | rev)
++    conf_name=$(basename -- "${kea_config_file}" | awk '{for(i=length($0); i>0;i--) printf (substr($0,i,1));}' | cut -f2- -d'.' | awk '{for(i=length($0); i>0;i--) printf (substr($0,i,1));}')
+
+     # Default the directory to --localstatedir / run
+     local pid_file_dir