Handle reserved names of entities internally while decompiling blueprint.

[abhijeetkaurav1st]

If any entity found with reserved name (Service, Package etc.), add some flag to then entity name. As reserved keyword should not be used in blueprint file.

Right now it raises error:

"/root/.local/lib/python3.7/site-packages/calm/dsl/builtins/models/entity.py", line 183, in __new__
    raise TypeError("{} is a reserved name for this entity".format(name))
TypeError: Package is a reserved name for this entity

Ex:

class Package(Package):
    pass

---

Package name should not be allowed in above case.

[abhijeetkaurav1st]

Take prefix from user and append to all entities. Ex: calm decompile bp --prefix Foo.