bitbake.conf: subversion cmds, remove --trust-server-cert and add --force, --accept

bitbake.conf: subversion cmds, remove --trust-server-cert and add --force, --accept

* --trust-server-cert is supported only in >=svn-1.6
  http://subversion.apache.org/docs/release-notes/1.6.html
* --force allows to overwrite existing dirs
  ie
  matchbox-panel-2-icon-themes_0.0.1.bb
  matchbox-panel-2_svn.bb
  are checkouting/updating tiwo different SRCREVs and every few builds
  you end up removing svn checkout from downloads dir, just because it
  refuses to upgrade to newer revision (applets dir already exists there).
* --accept to overwrite any local modifications (as we want clean checkout)

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>