Update install_erpnext.py

Update is_redhat variable becose distribution response with "red hat enterprise linux server" and response is False.
Merge pull request #1024 from dbinary/patch-1

[minor] Update install_erpnext.py
[minor] replace 'raise e' with 'raise' for correct tracebacks
[minor] [docs] fixes in filename and title
[minor] optimized webnotes.has_permission
[minor] removed remark field from auto material request
[minor] check permission for editable web page
[minor] [docs] fixed labels
[minor] [patch] save style settings
Merge branch 'documentation-website' of github.com:webnotes/erpnext into documentation-website