adding support for hasOneMapping
removing commented code
adding support to hasMany relation
changing hasMany and hasOne method signuture
Update README.md

Adding explanation about relations
changing hasOne and hasMany signature from 'from' to  'for'
resolving conflicts
adding some spec for custom enum conversion type
Merge pull request #1 from lucasmedeirosleite/master

Adding support to hasOne and HasMany relational mapping