This question is a little old but a few days ago I was dealing with this situation and found pgloader.io.
This is by far the easiest way of doing it, you need to install it, and then run a simple lisp script (script.lisp) with the following 3 lines:
/* content of the script.lisp */
LOAD DATABASE
FROM mysql://dbuser@localhost/dbname
INTO postgresql://dbuser@localhost/dbname;
/*run this in the terminal*/
pgloader script.lisp
And after that your postgresql DB will have all of the information that you had in your MySQL SB.
On a side note, make sure you compile pgloader since at the time of this post, the installer has a bug. (version 3.2.0)