[generator] change swift-specific namespace from 'swift' to 'java.swift'
[generator] Add a switch to gate usage of plain java namespace

Instead of always looking for a swift-specific namespace in a .thrift file, and always falling back to the java namespace in case there is no swift-specific namespace, after this change we'll only look for one or the other (by default we'll use the swift-specific namespace, but we'll use java if '-use_java_namepsace' is passed on the command-line)
[generator] Allow namespace selection from maven plugin
Merge pull request #63 from andrewcox/swift-namespace

Updates to generator namespace functionality
Upgrade to Airlift 0.70 and Netty 3.6.2.Final
[maven-release-plugin] prepare release swift-root-0.5.0
[maven-release-plugin] prepare for next development iteration
Use the nifty version from the dep.fb.nifty.version property again
Use nifty 0.6.0-SNAPSHOT
Provide a getRemoteAddress utility method on ThriftClientManager
Let parser generate null for missing integer fields

Integer tokens were generating java type 'long', returning 'Long' instead lets the parse tree contain null instead of zero for missing int values. This change enables existing code in the generator that fails on fields in thrift structs or parameters on thrift methods that don't have explicit identifiers.
Fix generation of enums using implicit values

If some or all of the values in an enum are not explicitly numbered, they should count up from the last explicitly numbered value (or from zero if no explicit value was seen yet).
Fix broken unit tests

Some unit tests classes I had at one point got running using IDEA didn't run in the maven build because surefire didn't match them as test classes by class name. These tests got broken. I'll be renaming them in the next commit, but this fixes the tests first so the maven build won't be failing when the class names are corrected.
Rename tests so they are run by surefire
[swift-idl-parser] Parse and accept default namespace
[swift-generator] Generate toString() for structs and exceptions
[swift-idl-parser] Default namespace should not be required

Fixes parser test failures caused by a mistake in my recent commit
[swift-generator] Fix generator imports
Update README.md to use relative links

GitHub supports relative links now:
https://help.github.com/articles/relative-links-in-readmes
[swift-generator] Generate "Void" instead of "VOID"