No distributions at all found for some package
I got the solution ,Try with --allow-unverified

syntax: pip install packagename=version  --allow-unverified  packagename

Some package condains insecure and unverifiable files. it will not download to the system . and it can be solved by using this method --allow-unverified. it will allow the installation.

Eg: pip install django-ajax-filtered-fields==0.5 --allow-unverified
  django-ajax-filtered-fields
error when installing some package but its actualy existing example django-ajax-filtered-fields==0.5

Downloading/unpacking django-ajax-filtered-fields==0.5 (from -r
  requirements.example.pip (line 13))   Could not find any downloads
  that satisfy the requirement  django-ajax-filtered-fields==0.5(from
  -r requirements.example.pip (line 13))
  No distributions at all found for django-ajax-filtered-fields==0.5  Storing debug log for failure in /home/pd/.pip/pip.log
  (peecs)pd@admin:~/proj/django/peecs$ pip install
  django-ajax-filtered-fields==0.5 --allow-unverified
  django-ajax-filtered-fields==0.5 Downloading/unpacking
  django-ajax-filtered-fields==0.5   Could not find any downloads that
  satisfy the requirement django-ajax-filtered-fields==0.5   Some
  externally hosted files were ignored (use --allow-external
  django-ajax-filtered-fields to allow). Cleaning up... No distributions
  at all found for django-ajax-filtered-fields==0.5 Storing debug log
  for failure in /home/pd/.pip/pip.log