Add option to send mails without authentication
Fix formatting
Email should retry on SocketTimeoutException  - issue #322
Emailer calls AbstractMailer for useAuth property
Removed usesAuth variable from Emailer
Enable gzip compression on *DistTar tasks

Gradle now produces valid GZipped Tar archives.
Tested by running `./gradlew distTar` on Ubuntu 14.04.

Fixes #263
Implement azkaban project validation plugin.
Refactor DirectoryFlowLoader to become the default project validator.
Updated code based on code review feedback
Merge pull request #311 from ReccaHokage/email-no-auth

Add option to send mails without authentication
change the default max attachment size to more readable
Simplify max attachment size checking logic
changes due to method name change in EmailMessage class
Merge pull request #324 from wndhydrnt/fix_distTar_gzip

Enable gzip compression on *DistTar tasks
Fix the comments received in the pull request (#326).
Change the <item> tag inside the validator xml configuration file to <property>.
Change the way test cases deal with expected Exceptions to make the code cleaner.
rebased from upstream to merge with useAuth flag changes
Remove SuppressWarnings Annotations in the test case.
Change the name and comment of the method that fetches the name of a ProjectValidator to make them more accurate.