Change the default behaviour of all scripts to NOT fetch.

This already was the default behaviour of git-flow-feature, but now it
is the default for the other scripts, too.

RATIONALE: Due to limitations on some platforms (and some
implementations of getopt), it's impossible to turn off the -f (fetch)
option.  Therefore, it must now be set explicitly.

Also, this makes git-flow work in stand-alone repositories (i.e. repos
that do not have an origin remote at all).
diff --git a/git-flow-support b/git-flow-support
index 1ec1b4e..ba92cb9 100644
--- a/git-flow-support
+++ b/git-flow-support
@@ -156,7 +156,7 @@
 }
 
 cmd_start() {
-	DEFINE_boolean fetch true "fetch from $ORIGIN before performing finish" F
+	DEFINE_boolean fetch false "fetch from $ORIGIN before performing finish" F
 	parse_args "$@"
 	require_version_arg
 	require_base_arg