Adding external indexes

In Hyracks side, this change include the following:
1. The addition of three indexes:
 a) external b-tree index
 b) external r-tree index
 c) external b-tree with buddy b-tree index
2. creating an additional logical operator in algebricks for performing lookup operations over external data and modify the different visitors to work with this operator

3. Added copyright header to all new files

Change-Id: Iecfbd86f06aff3caaf3a9652b63420666745ebb9
Reviewed-on: http://fulliautomatix.ics.uci.edu:8443/69
Tested-by: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Reviewed-by: Zachary Heilbron <zheilbron@gmail.com>
Reviewed-by: Sattam Alsubaiee <salsubaiee@gmail.com>
Reviewed-by: Ian Maxon <imaxon@uci.edu>
66 files changed
tree: 9fcb1692f49a1bf2d9c15b36bb28a2da1bef60aa
  1. .gitignore
  2. algebricks/
  3. hivesterix/
  4. hyracks/
  5. pom.xml
  6. pregelix/