nuxeo-dm is a sub-module of the root Nuxeo project. Try building the complete Nuxeo source by cloning https://github.com/nuxeo/nuxeo and following the README.md of that project, specifically the Deploying section. Please make sure the machine you are building on has all of the Requirements, make sure you run the clone.py script, and add -DskipTests to your Maven parameters to save time on the build. The result will yield compiled jar files for all of the Nuxeo modules. Building the nuxeo-distribution/nuxeo-distribution-tomcat sub-module will yield a deployable distribution (nuxeo-distribution-tomcat-7.10-SNAPSHOT-nuxeo-cap.zip)

The CORG/Getting+the+Nuxeo+source+code documentation recommends export MAVEN_OPTS="-Xmx4096m -Xms1024m -XX:MaxPermSize=512m" but it depends on your OS and material.

Actually, I'm wondering what is your goal? What do you want to achieve? The source code is under continuous integration at Nuxeo QA and the generated artifacts are published into the Nuxeo Maven repositories, so there are very few reasons to build the whole Nuxeo Platform yourself.