Initial commit
Initial import
Remove duplicate license text
Adjust verbosity of compilation output
Add ModelObserver and observer tests for Account

As a side-effect ObservableModel::{will,did}ChangeValueForKeyEvent were
changed to Poco::BasicEvent<const string>
Cleaned up Account tests
Add test for AccountsMeta and event firing

Related changes:
* extracted TestModelObserver into separate class, shared between tests
* removed const from getAccountsMeta() return value: not needed since
there are no public setters in AccountsMeta anyways. It was causing
issues to attach the TestModelObserver since adding an event delegate is
technically modifying the object.
* now odb-related code uses setter methods in Account class
Initialize document with root account
Add unidirectional relationship Account.parent
Add bidirectional parent-children for Account

The following changes were necessary:

* Add `children` property to Account
* Make Account inherit from ::std::enable_shared_from_this<Account>
* Specify ODB-specific `pointer(std::shared_ptr)` for Account
* Change pointers to Account to shared_ptr (from unique_ptr)
* Wrap accounts retrieval into an ODB session
Fix for Account.setParent event trigger
Fix forgotten assert, rename tests
Replace TestModelObserver by gmock
Add support for to-many observing
Rename observer methods
Improve encapsulation for ObservableModel._model
Remove using declarations and directives from header files (closes #1)
Add class-local type definitions through using aliases (closes #2)
Renamed Account.description to descr due to name clash on mac/ios
Prepare POCO for cross-compiling to iOS