Allow fine grained control over used signing services

EPP uses all three currently available signing services from at the
Eclipse Foundation. The general signing service to sign the jar files,
the Windows signing service for the Windows executable, and the Mac OSX
signing service for various Mac-related signatures.

With this change it is possible to control by enabling Maven profiles
which signing services are used during build time.

Bug 451139: Unable to sign Mac OSX packages from EPP HIPP instance
https://bugs.eclipse.org/bugs/show_bug.cgi?id=451139

Change-Id: If2ccd76d85aec2136520e4cbdd397115fa36fb01
Signed-off-by: Markus Knauer <mknauer@eclipsesource.com>
Update build to Tycho 0.21 and CBI 1.1.1

Change-Id: I566e36ff4d6bae43f8778bc265e2415a8644914c
Signed-off-by: Markus Knauer <mknauer@eclipsesource.com>
Update for Mars M3 (configuration files, ...)

Change-Id: I0e5d8c7f523c73988b92eb69699411b617c7a982
Signed-off-by: Markus Knauer <mknauer@eclipsesource.com>