Add tags support

Add support for "tags" field of files and folders, and "my_tags" field
of users.
Add .travis.yml
Merge pull request #73 from gcurtis/travis

Add .travis.yml
Adding Login_Token resource type
Merge pull request #71 from mmorearty/tags

Add tags support
modify unit tests for the tag support
Merge pull request #75 from box/addutest

modify unit tests for the tag support
update javadoc
Merge pull request #76 from box/jd

update javadoc
Updated name
Merge branch 'master' of github.com:box/box-java-sdk-v2 into login_token
Merge pull request #77 from box/login_token

Add Login Token resource type
get rid of getTotalCount() in events collection, for streaming events, there's no total_account.
Merge pull request #78 from box/total

get rid of getTotalCount() in events collection, for streaming events, t...
monitored restclient
fix bug that monitor thread cannot be terminated
share a same ConnectionManager
synchronize on getting connection manager instance
support IBoxType as generic interface of BoxResourceType's
make BoxResourceHub easier to be extended