Added "prepare-release" build target, made b2.6 depend on the latest from b2.6-sdk



build.xml:
Added targets "prepare-release", "check-no-snapshot-dependencies" and "resolve-snapshots-separately".

ivy.xml:
Now depends on the latest from b2.6-sdk.




Sample output on failure:
------------------------------------------------------------------------
branches/b2.6 $ ant prepare-release
Buildfile: /opendj2/branches/b2.6/build.xml
Trying to override old definition of task javac

clean-lib:

check-ivy-installed:

download-ivy:

install-ivy:

resolve-snapshots-separately:
[ivy:retrieve] ...
[ivy:retrieve]  23 artifacts copied, 0 already retrieved (9038kB/30ms)

check-no-snapshot-dependencies:

BUILD FAILED
/opendj2/branches/b2.6/build.xml:2775: The project must not depend on snapshot dependencies. Found: opendj-ldap-sdk-2.6.5-SNAPSHOT.jar;opendj-rest2ldap-2.6.5-SNAPSHOT.jar;opendj-rest2ldap-servlet-2.6.5-SNAPSHOT.jar;opendj-server2x-adapter-2.6.5-SNAPSHOT.jar
------------------------------------------------------------------------




Sample output on success:
------------------------------------------------------------------------
[ivy:retrieve]  23 artifacts copied, 0 already retrieved (9038kB/28ms)

check-no-snapshot-dependencies:
     [echo] OK.

prepare-release:
     [echo] 
     [echo] Previous checks succeeded.
     [echo] 
     [echo] Please:
     [echo] 1- Check the archive has no build number
     [echo] 2- Check the archive contains the license
     [echo] 3- Run the tests
     [echo] 4- Check that documentation refers to forgerock.com instead of forgerock.org
     [echo]     
------------------------------------------------------------------------