unit and functional tests on validate.py

[prasadtalasila]

Create unit and functional tests on validate.py.

[Kausam]

The commit d8e2add merged into master has some bugs in it. This causes the ubuntu driver to fail when run.
The errors are:

1. This line requires start_date to be a datetime object whereas actually it is a string. This causes an AttributeError. Similar issues are in other functions of validate.py
2. It prints [Error | io/linuxInput] Channel /home/irc_logs/ubuntu/2013/01/01/#.txt doesn't exist [Error | io/linuxInput] Channel /home/irc_logs/ubuntu/2013/01/01/k.txt doesn't exist [Error | io/linuxInput] Channel /home/irc_logs/ubuntu/2013/01/01/u.txt doesn't exist [Error | io/linuxInput] Channel /home/irc_logs/ubuntu/2013/01/01/b.txt doesn't exist [Error | io/linuxInput] Channel /home/irc_logs/ubuntu/2013/01/01/u.txt doesn't exist [Error | io/linuxInput] Channel /home/irc_logs/ubuntu/2013/01/01/n.txt doesn't exist [Error | io/linuxInput] Channel /home/irc_logs/ubuntu/2013/01/01/t.txt doesn't exist [Error | io/linuxInput] Channel /home/irc_logs/ubuntu/2013/01/01/u.txt doesn't exist [Error | io/linuxInput] Channel /home/irc_logs/ubuntu/2013/01/01/-.txt doesn't exist [Error | io/linuxInput] Channel /home/irc_logs/ubuntu/2013/01/01/d.txt doesn't exist.