added error messages if etherpadlite.apikey or wkhtmltox.path is missing in the config
Merge branch 'exportObject' of https://github.com/winfel/wa_knowledge_structuring into exportObject

# By Alejandro Sandoval Parra (2) and Sharath (1)
# Via Sharath (2) and Alejandro Sandoval Parra (1)
* 'exportObject' of https://github.com/winfel/wa_knowledge_structuring:
  little change
  I corrected the name of the variable that points to the start.bat file
  Fix error when creating PDFs