Hi people!

I have been working on my TinyDTLS branch on the last days.

This PR brings 3 things:

1. RIOT will uses my TinyDTLS master branch by default instead of a specific commit.
2. The default example has a series of fixes and is saving a little more of memory now.
3. The current configuration (only PSK mode and TinyDTLS' debug messages disabled) is more stable. Probably due to other PRs related to hardware performance.

I have been speaking with @kYc0o about what is next and for now is increasing the stability for ECC. But probably, that will be reflected only on my TinyDTLS fork. After that, I'll try again with sock.

The merge conflict for this PR is in pkg/tinydtls/Makefile:

PKG_NAME=tinydtls
PKG_URL=https://github.com/rfuentess/TinyDTLS.git
<<<<<<< HEAD
# PKG_VERSION=RIOT-OS
PKG_VERSION=d06ad84d3e8bd3e86f7557faee34b68d5f8c0129
=======
PKG_VERSION=master
# (Official) Branch with tested(?) updates before merging to remote master
#PKG_VERSION=RIOT-Tested-Upgrades

>>>>>>> TinyDTLS-Upgrades02b
PKG_LICENSE=EPL-1.0,EDL-1.0

.PHONY: all

all: git-download
       $(MAKE) -C $(PKG_BUILDDIR)

include $(RIOTBASE)/pkg/pkg.mk