fs: pipe: Add code to flushing

Signed-off-by: Bart Kuivenhoven <bemkuivenhoven@gmail.com>
lib: tree: Add thread safety to the tree structure

Signed-off-by: Bart Kuivenhoven <bemkuivenhoven@gmail.com>
Merge remote-tracking branch 'avl/master' into pipe

Ported thread safety over to andromeda dependencies

Signed-off-by: Bart Kuivenhoven <bemkuivenhoven@gmail.com>

Conflicts:
	.gitignore
	src/lib/avl/Makefile
	src/lib/avl/tree.c