Add hello-world exercise

Add new exercise pangram

Based on code review feedback.

This implementation does not generate a test suite based on the json
meta the hello-world exercise.
See https://github.com/exercism/todo/issues/13

Fixes https://github.com/exercism/todo/issues/35

Add ABOUT.md documentation to describe the Java language.

crypto-square: Fix invalid tests

allergies: Add test case to check when not allergic to anything

atbash: Add test case and sample implementation for decode.

(contributes to #53)

Needed to run the x-api, locally.

the github styles already have ruling lines for h1 and h2s.

- where files are required from the "starter" (./src/main/java), these
  are now soft-linked into the example source.
- a couple examples were missing import statements.
- the example code for Hamming was failing the test suite.

At this time, these are all of the problems that have example code.

- without this output, another contributor might make the reasonable
  (but incorrect) assumption that the source being compiled to exercise
  the tests are from 'src/main/java'.

- enable compilation during CI build only for those that currently pass.
  (let's tackle the failing tests+example code one at a time).

- adjusted "etl" as it has "starter" code.

- move example.java so we can refer to it in Gradle as a soureSet.
- Java requires public classes be contained in identically-named files.
- using latest Travis infrastructure (better, stronger, faster).
- each piece of travis config has been confirmed as minimum necessary at
  this time.
  - without JDK specified, would run with default (Java 7)
  - without TERM=dumb, travis output is unreadable.

Fix regex to only allow uppercased letters for the the first 2 characters.

[robot-name]

Corrected error in RandonKeyCipherTest.java

I changed the cipherKeysAreRandomlyGenerated test so that it does not compare the new Cipher to the length of the old Cipher.

An anagram is defined as

1. the same letters
2. rearranged
3. to make a new word

The existing assertion only checked the presence of the expected word,
but did not explicitly exclude the existence of results that match the
input exactly.

- Especially in the earlier exercises, let's make it one less
  error that folks need to track down.

(fixes #54)

scrabble-score: replace illegal word

multibillionaire can't be played as a word in a real scrabble game.

Revert "Move example source into a conventional source root location."

This reverts commit c2657807be96bc6aecfc34781ca6963477b1fe29.

If we want to do this, we'll need to do it more systematically to
avoid breaking the build and confusing people who may be used to
finding the solution in a particular place.

- includes @Parameters attribute that allows you to define a template for names of tests, making the test output far easier to follow.

- makes it easier to work on a solution when you can one-step define the source root containing the example.
- one step toward making it easy to run unit tests against example solutions in CI.

- fixes exercism/x-api#59

Define the missing class (with no content)