Replace tab to 4 spaces

All py, css, js, tmpl and json files created by us must use 4 space for
indentation.
Imported files must keep as they are (such as those for jquery, novnc)

This patch was generated by the following command:

find . -name \*.py -o -name \*.json -o -name \*.css -o -name \*.js -o \
       -name \*.tmpl | xargs -I @ sed -i s/\\t/"    "/g @

Then imported files had changes reverted.

Signed-off-by: Aline Manera <alinefm@br.ibm.com>