Added ConstraintSpace interface implemented by ReifiedSpace
"This is used when executing search from gecode"
Added inject builtin in the space module
This builtin is still in development, yet to be added asertions and others things.
Added dfs builtin in search module
This builtin finds one solution of a given script using depth first search from gecode.
TODO: Reflect the solution to the OPI.
Merge pull request #6 from miavisa/css

Css Space search and inject.