[packages] miredo: various fixes and cleanup

[packages] miredo: various fixes and cleanup
 * force use of shared libraries, remove obsolete configure args
 * add a miredo-common package for shared libraries (libteredo & libtun) (closes: #7761)
 * install config file in /etc/miredo/ (default) instead of /etc/
 * use default config file location in initscripts, remove useless ipv6 & tun modules loading in start functions
 * use PKG_INSTALL
 * bump release number

git-svn-id: svn://svn.openwrt.org/openwrt/packages@22639 3c298f89-4303-0410-b956-a3cf2f4a3e73