Set empty sku not as new

Bug in update of an existing products over multiple store views
Merge pull request #27 from cmuench/patch-1

Set empty sku not as new
[~TASK] Added example for customer import
Merge branch 'master' of github.com:avstudnitz/AvS_FastSimpleImport

# By Andreas von Studnitz (1) and Christian Münch (1)
# Via Andreas von Studnitz
* 'master' of github.com:avstudnitz/AvS_FastSimpleImport:
  [~TASK] Added example for customer import
  Set empty sku not as new