Fix DoctrineDriverTest random failures

Do not compare "created" timestamps of class metadata as it may fail
test on busy CPU
Merge pull request #155 from eugene-dounar/fix-doctrinedriver-test

Fix DoctrineDriverTest random failures
Allow deserialization to constructed objects

Pass DeserializationContext to object constructors.
Merge pull request #160 from eugene-dounar/pass-context-to-constructor

Allow deserialization to constructed objects
Update CHANGELOG.md
Update UPGRADING.md
Add virtual properties yaml example
Merge pull request #163 from adrienbrault/patch-2

Add virtual properties yaml example
some cs fixes
Fix inline bug with empty child
Merge pull request #165 from adrienbrault/inlining-fix

Fix inline bug with empty child
Metadata filename convention added to yml/xml references
Merge pull request #172 from rodrigodiez/master

Metadata filename convention added to yml/xml references
Add PropelCollectionHandler + tests
Merge pull request #81 from zebraf1/master

Support PropelCollection serialization
Update CHANGELOG.md
composer is preinstalled, but just to be extra sure, lets update it to the latest version
Merge pull request #185 from lsmith77/patch-1

composer is preinstalled on travis
fixes typo
When serializing into the xml the string property can be marked as not to be enclosed inside CDATA
Also fixed a bug where property metadata was not pushed onto the stack