Added test demonstrating issue #28
Fixing issue #28
Updated md.restx.json & module.ivy accordingly to pom.xml
Introduced WebServerSupplierFactory,
@Machine allowing to gather available WebServerSuppliers in SPI
Provided jetty/tomcat/simple web server suppliers
in their own modules
Removed hard dependency from restx-spec-tests to restx-server-jetty
Keeping it for unit tests in this module.
The restx-spec-tests user will have the choice to use the server impl of its choice
simply by adding the restx-server impl in the classpath.

BACKWARD COMPAT breaks out here : some RestxSpecRule & RestxSpecTestServer
disappear since they were too much related to a restx-server-jetty impl
In order to fix it, in most of cases, using the no-args constructor (relying on default
WebServerSupplier config) or constructor with a WebServerSupplier (using the one provided in
your restx-server artefact) would fix the issue.
Created new module restx-servers-testing,
allowing to provide a unique entry point for generic restx-server scenarii

Note that we don't have the choice to create a dedicated module for this,
because otherwise, maven will complain with circular dependencies between
restx-specs-test -(test)-> restx-server-jetty -(test)-> restx-specs-test
Made some naming refactorings in restx-server modules
fix NPE due to factory not being bound on query
Deleted useless WebServerSupplierFactory
Created UUIDGeneratorFactory, FactoryMachine providing utility classes
for manipulating named UUIDGenerators in Factory.

It will allow to define several named UUIDGenerators, and provide utility methods
to replace temporarily a named UUIDGenerators by another one, by playing with a
temporary added machine with a low priority.
This will allow, for instance, uuid generators playback mode in unit tests

Important note : ATM, temporary added machines are added to a specific context named
"uuidGeneratorsLocalMachinesContext". It could be improved in the future if we could
settle sort of "session affinity" between client (tests) and server (restx) for contextual
local machines
Refactored UUIDGenerator class by removing ThreadLocal behaviour
which is incompatible with a client (test) / server (restx) mocking.

Relying, instead, on the new UUIDGeneratorFactory by retrieving
UUIDGenerator components for exception & session resource
uuid generation (which could be overriden during unit tests).

Other impl relying a on UUIDGenerator (namely shell & RestxSpecTestServer)
which should not be overridable, will remain to rely on the UUIDGenerator.DEFAULT
instance.
Added new checkContainsKey precondition
Implemented new given uuid spec rule,
allowing to playback generated UUIDs by UUIDGenerators
Updated restx-server-testing in order to demonstrate usage of given uuids
Now we can add the generated session id as an expectation, during new session creation
Merge pull request #30 from fcamblor/cookies-issue-28

FIX #28: security issues on simple server
Merge pull request #32 from fcamblor/webserver-supplier-refacto

Removing hard dependency from restx-specs-test to restx-server-jetty

The restx-specs-test rules will then rely either on `@Procuced WebServerSupplier` (if no `WebServerSupplier` is passed as a constructor arg to the `@Rule`)

Important note : this introduced a backward incompat in restx-spects-test `@Rule` constructors, too much tied to the restx-server-jetty implementation, which was removed.

To fix this, you will either have :
- To use simple default constructor which will rely on default web server config available in classpath
- To provide a WebServerSupplier by hand if you want to override default web server config

Another backward compat is `ServerSuppliers` utility class doesn't exist anymore: `WebServerSupplier` can be retrieved directly from the restx-server-* utilities (for instance, `JettyWebServer.jettyWebServerSupplier()`)
tomcat: add dependency on restx-servlet

this dependency is required to run a restx app in tomcat
FIX: simple server impl does not handle cookies properly (Fixes #29)

Cookie values were not escaped properly in spec tests, and Simple server does not unescape them either.
Simplified UUIDGeneratorFactory
Not being a useless FactoryMachine anymore
Thus, renamed to UUIDGenerators since this is only a helper class
about UUIDGenerators in DI contexts