Eligibility criteria tags support conditions with 'AND' only and not 'OR'

[nirmalnr]

For example current tag structure supports the following:

• User must have 60% in 10th
• User must have 60% in 12th
  Here the user must have above 60% in both 10th and 12th

It does not support the below:

• User must have minimum 60% marks in undergraduate or postgraduate studies