Detect if command line argument is null value

If any of the command line argument is null value or string "null",
Error manager will report errors and stop Arrow execution with exit
code 1.
Check more command line argument issues.

Now, empty string and undefined value are also invalid command line
argument value.
Adding log statements
Fixing console statement
Adding descriptor path in log statement
Removing thisSession variable, enhancing log statements
Fixing console statements
Improving console log
Improving console logs
Adding more console logs
Adding callback for error handling
Merge pull request #136 from bowdev/error_1004

Error 1004
Merge pull request #137 from bowdev/null_argument

Detect if command line argument is null value
Improving Arrow doc
Adding more documentation
Cleaning up console statements
Cleaning up to sync with master
Cleanup
Fixing test failure, changing error handling when webdriver has quit
Adding callback error handlers