added basic version for the LINDEX, LPUSH and LSET command
Implemented _lwalk from right

Fixed the LINDEX and LSET commands with negative offsets.
added examples and related functions for LINDEX, LPUSH and LSET
Implemented LLEN command
Implemented LPOP command
Implemented RPOP command
Implemented RPUSH command
Renamed RPOP and RPUSH commands
Implemented LINSERT command
Refractored LINSERT command
Added LINSERT as related command
Fixed keyinfo for LINSERT at first and last position
removed _checkttl function call from _lwalk
implemented private list insert method _lins
Implemented LGET command
Renamed _lins to _linsert
Added LDEL command
Merge pull request #10 from semfact/lists

Lists