Local installation with distuilts assign wrong prefix

[ebayer]

When installed with distutils, files are installed into /usr/local. enlinuxclipper/common.py needs to be updated by distutils according to installation prefix:

Traceback (most recent call last):
File "/usr/local/lib/python2.7/dist-packages/enlinuxclipper/indicator.py", line 142, in open_preferences
Preferences()
File "/usr/local/lib/python2.7/dist-packages/enlinuxclipper/preferences.py", line 36, in init
self.init_ui()
File "/usr/local/lib/python2.7/dist-packages/enlinuxclipper/preferences.py", line 41, in init_ui
builder.add_from_file(DIR_PREFIX + '/share/en-linuxclipper/preferences.ui')
File "/usr/lib/python2.7/dist-packages/gi/types.py", line 113, in function
return info.invoke(_args, *_kwargs)
gi._glib.GError: Failed to open file '/usr/share/en-linuxclipper/preferences.ui': No such file or directory