Fixed: test_each_profile(Image2_UT) in Image2.rb fails #73

### Error

```
test_each_profile(Image2_UT) [/home/linduxed/Documents/ruby/rmagick/test/Image2.rb:447]:
<"8BIM\x04\x04\x00\x00\x00\x00\x01\xE0test profile"> expected but was
<"test profile">.
```

### Cause
from: ImageMagick 6.6.4-5
changed: 8bim -> iptc
ImageMagick 6.6.4-5 source: coder/jpeg.c

In ReadIPTCProfile function: 
```
-      status=SetImageProfile(image,"8bim",profile); 
+      status=SetImageProfile(image,"iptc",profile); 
```

<a href="http://trac.imagemagick.org/changeset/2667">Changeset 2667 – ImageMagick</a>

<a href="http://trac.imagemagick.org/browser/ImageMagick/trunk/coders/jpeg.c?rev=2667#L439">jpeg.c in ImageMagick/trunk/coders – ImageMagick</a>


Therefore, <"test profile"> is correct from ImageMagick 6.6.4-5.