Update install_erpnext.py

Update is_redhat variable becose distribution response with "red hat enterprise linux server" and response is False.
[report] [fix] accounts payable fixed for get_ageing_date()
Merge pull request #1026 from akhileshdarjee/1310

[report] [fix] accounts payable fixed for get_ageing_date()
Merge remote-tracking branch 'origin/1310'
[minor] fixes after remark field removal
Merge branch 'master' of github.com:webnotes/erpnext
[ui cleanup] [minor]
[cleanup] [ui] minor
Update accounts_payable.py
update install docs
[minor] favicon
[docs] knowledge files and faq
Merge pull request #1030 from fogueri/master

[docs] knowledge files and faq
Merge pull request #1024 from dbinary/patch-1

[minor] Update install_erpnext.py
Update sales_analytics.js

Fix a error caused after the translation.
Merge branch 'master' of github.com:webnotes/erpnext into discount_amount
[docs] faq repacking
Merge pull request #1039 from fogueri/master

[docs] faq repacking
Merge pull request #1035 from MaxMorais/patch-1

[minor] by Max - fixes after translation in sales_analytics.js
[cleanup] Fixed title bars, toolbars in all pages, added default background