Add linting support

[michael-kamel]

Fixes #11 There are many options for formatting / linting and no go to standard solution. I used a basic Sun style checkstyle configuration in this pr. Maybe we can use something like SonarQube instead for managing overall quality?

• No tabs allowed
• Allowed length up to 100
• Disabled DesignForExtension(too defensive)
• Allow no doc for methods with up to 5 lines.
• I ended up disabling the check for method docs as I found that is it a bit too restrictive for what we are doing. Furthermore, the goal of this is not to enforce docs, but to maintain a consistent style.
• Disabled FinalParameters (While is it intuitively a good practice to not modify params, it is too defensive. This should be allowed but the developer should take responsibility to document any workarounds/hacks that utilize this)
• Ignored annotation magic numbers
• JavadocPackage(not worth stalling builds for)
• Disabled checks for test files(we probably need to refactor our tests anyway so no point in doing this right now)

Additional changes

• ignored line length checks for annotations
• Only check number of parameters for methods not constructors
• Allow public final field

Final Changes

• Extended line length to 120
• Removed lines with only an operator on them

[chaoran-chen]

I like the style :)

[vordemann]

Sun style checkstyle looks good

[vordemann]

Adjustments: no tabs, and line size amend

[BJRWolf]

looks good