Merge pull request #282 from jcla1/master

Added quicksort in Prolog
heap sort in Erlang, Perl, Python & Ruby
Merge sort in Perl
Merge pull request #283 from Sweet-kid/master

Merge sort(in Perl) & heap sort (in Perl, Python, Ruby & Erlang)
Merge pull request #284 from jcla1/master

Added Euclidean Norm in Python