After many trials of upgrading to Bluez5 I would strongly recommend not upgrading yet, there are too many issues for a stable system. Still having said that, here is what you will get at present if you will to upgrade.
Install the above PPA from vidplace7 and perform the usual process;
sudo apt-add-repository ppa:vidplace7/bluez
then update the software lists:
sudo apt update
Then upgrade your installed software:
sudo apt upgrade
At this point, apt will probably hang on unpacking the new Bluez5 package. There is nothing you can do at this point, hard shutdown the computer and reboot.
After rebooting, you will need to run:
sudo dpkg --configure -a
This will unlock apt... Then you will need to open the file manager as root and navigate to /var/lib/dpkg/info/, then delete every file that starts with bluez. Once you do that, open the terminal and run the upgrade command again.
sudo apt upgrade
This time it should install the new Bluez5 packages. Note: because the ppa is update very often, every time you upgrade your software it will hang at the unpacking of the new Bluez5 package. So you will need to delete all of the bluez files in /var/lib/dpkg/info/ again. To avoid this issue, just type Software & Update in Slingshot, find the ppa and un-check the ppa to disable it. You can then run it every once and a while or as needed.
Now, the Bluetooth indicator will no longer function so you will need to install Blueman version 2.0> , if you are on a 64Bit system, use this one: http://ftp.us.debian.org/debian/pool/main/b/blueman/blueman_2.0-1_amd64.deb
Once this is all setup, you should be able to pair and use the latest "Smart" bluetooth mice using Blueman to set them up.
All Bluetooth A2DP (Audio sync) capabilities will be lost, because Pulse Audio for Bluez5 is not yet available.
If you go through all fo this and it does not work for you, just delete the ppa and type:
sudo apt-get purge bluez
If the system hangs again, jsut delete the files in /var/lib/dpkg/info that start with "bluez" and try again. once that is done, run:
sudo apt update & sudo apt upgrade just to make sure everything is working.
Then reinstall bluez and indicator using the following commands:
sudo apt install bluez
sudo apt install indicator-bluetooth
This should restore your system to previous state.