Initial commit of Particles classes.
Fixed bug -- no super call from Particle and Bond classes
Modified deep copy of low level objects.
Modified name of 'ABCParticlesContainer' and 'ParticlesContainer' to 'ABCParticleContainer and 'ParticleContainer' due to another developer request
Changed 'x', 'y', 'z' attributes of Particle for a 'coordinates' attribute.
Fixed equal operator for particles and bonds, and removed the others since we dont need them for now. Added a property in the base class 'ElementsCommon' for the id making it read-only for the moment.
Added more info in exceptions and errors.
Merge branch 'master' of https://github.com/simphony/simphony-common into feature-particles
Fixed test_particlesclasses.py file for travis-ci support.
Changed id behaviour according to Wiki
Fixed bug in Bond
Fixed issues according to github suggestions.
Merge remote-tracking branch 'origin/master' into feature-particles
Fixed issues according to github suggestions.
Fixed flake8.
Replaced Custom Exceptions for Built-in Exceptions.
Fixed doc.
Removed equal operators, overriden methods in tests and empty sections in doc.
Simplified Particle and Bond classes, removing Element. Updated docstrings. Updated/implemented tests.
Merge branch 'master' into feature-particles