Ensure Bash is used when spawning terminals

We rely on Bashisms when spawning a terminal so ensure that bash is used
when using devshell and menuconfig.

Fixes [BUGID #119]

Signed-off-by: Joshua Lock <josh@linux.intel.com>

meta/classes/devshell.bbclass

@@ -9,7 +9,8 @@ devshell_do_devshell() {
 	export XAUTHORITY='${XAUTHORITY}'
 	export TERMWINDOWTITLE="Bitbake Developer Shell"
 	export EXTRA_OEMAKE='${EXTRA_OEMAKE}'
-	${TERMCMD}
+	export SHELLCMDS="bash"
+	${TERMCMDRUN}
 	if [ $? -ne 0 ]; then
 	    echo "Fatal: '${TERMCMD}' not found. Check TERMCMD variable."
 	    exit 1
@@ -17,6 +18,5 @@ devshell_do_devshell() {
 }
 addtask devshell after do_patch
 
-
 EXPORT_FUNCTIONS do_devshell