Adding Ubuntu dependencies instruction to Readme.

Adding link section at the end of the Readme.
Using links in Readme dependency list.
Improving clarity in running instructions.

Correcting run all path in running instruction.
Simplifying Ceres Ubuntu instructions.

Adding links to gflags and glog packages.
Moving SuiteSparse information to Ceres part since it belongs there.
Merge pull request #4 from oscarlorentzon/feature/readme-ubuntu

Update of Readme with Ubuntu instructions