[Bf-committers] regression fix for collada

[Gaia]

Hi;
i found that some collada files with missing armature now are completely 
rejected by the Blender collada importer.
Up to Blender 2.72b these meshes where imported but without animation 
data (weight maps).
btw: Autodesk tools import these meshes just fine (including the weight 
maps)

For 2.73 i propose to partially revert to the 2.72b behavior.
This commit should do it:

f78490182efc5d4c1145321f449cbd0d7fb08bb6

For 2.74 i can look into this again and try to import the mesh animation 
data as well.

-gaia-