added eclipse repository for finging element-connector jars

Signed-off-by: Julien Vermillard <jvermillard@sierrawireless.com>
Remove keystore loading code from handshakers

The client and server handshaker class was loading keystore and
truststore. I removed this code, the store need to be given at
DTLSConnector creation.

It's removing clutter from the handshaker classes and help to understand
how/who/where the key are loaded (single responsability principle)
Removing setting in ScProperties

Removed default port:
In fact DTLS have no default port, this settign doesn't really make
sense.

Removed DTLSConnector settings since it's the main facing API and it's
simple to use setter/getter.
Killed ScProperties

now you configure everything using the Java API of DTLSConnector
Refactoring of the DTLSConnector configuration.
Added a server integration test

This test is disabled by default, you need to use
a special profile for running it.

It's meant to be ran versus a dtls client (like
tinydtls).

I'll provide tooling for running this test as a
separate commit/project.