Updated IntelliJ setup with missing step

Clarified steps to setup IntelliJ by adding in missing step.
Add missing import to docs
Scaladoc and specs for SQL statement parser
Improve wording

As suggested by Byron Becker at
https://groups.google.com/d/msg/play-framework/yzwBa2afFcs/9r8UoUwjP-QJ
Merge pull request #2272 from philwills/json-transformer-doc-tweak

Add missing import to docs
'optional' mapping description has been  appended

appended 'optional' mapping constraints description
Upgrade Akka to 2.3.0-RC1

- Upgrade Akka to 2.3.0-RC1
- [Add parens to `sender` reference as recommended]
  (http://doc.akka.io/docs/akka/2.3.0-RC1/project/migration-guide-2.2.x-2.3.x.html#Parens_Added_to_sender)
Fix removed or deprecated Akka Java API
Merge pull request #2271 from georgiknox/patch-1

Updated IntelliJ setup with missing step
Merge pull request #2281 from cchantep/anorm-stmtparser-specs

Scaladoc and specs for SQL statement parser
Merge pull request #2284 from fernandoacorreia/update-doc

Improve wording
Merge pull request #2288 from guersam/tmp/akka-2.3

Upgrade Akka to 2.3.0-RC1
ToSql and sequence support
Merge pull request #2285 from cchantep/anorm-prepsql-paramseq

ToSql and sequence support
Create Java Mode enum