First version of server-side reactive context
Many changes (reactive model WIP)

- App is now passed as a class and not an instance
- App now runs on_start() classmethod on app start
- App now runs on_init() method on client connection
- updated example.py
- enabled angularjs $log service
- moved context-specific/socket stuff to Context service
- update bower dependencies to latest versions
Created "unsafe" $sce filter to accomodate for angular 1.2.0
Added coffeelint to build task, linted all .py and .coffee files
Removed test file
Don't import gevent from IPython session (for debugging purposes)
It's not too stable but it kinda works (first version of observers/outputs)
Big time work on reactive engine + unit tests

- Refactored all reactive classes
- Moved all methods from environment to context
- expression(), value(), observer() methods now have prefix "new_"
- expression() and value() are now decorators
- reactive values are now required to be initialized with a value (may
be changed?)
- added 7 unit tests from shiny testsuite
- added logging capability to reactive context
- fixed a humonguous amount of bugs with reactivity
- more careful handling of UndefinedKey
- context now tracks running observers/expressions so reflushing
doesn't happen if not needed
- fixed a bunch of reactive/non-reactive recursion edge cases
- updated app.py and both examples
Added environment isolation + more flexible constructors

- env[:] now returns an isolated environment (doesn't register caller
as parent)
- new_* object constructors can now be called as new_value('a', 1, 'b',
2, c=3, d=4)
- set_value can now also be called as above
- added some unit tests to cover that
- added isolation unit tests from shiny
More tests, 99% coverage
100% reactive engine coverage
Added value formatter for context log, got rid of pandas dependency
Added environment block isolation with ~ and [...] operators
Added observer suspending/resuming feature
In "safe" mode, context tracks cryptographic hashes of env

- added joblib dependency
- removed blinker dependency
- added context safe/unsafe option (safe by default)
- objects are now hashed using joblib.hashing.hash
- subclassed ReactiveExpression/ReactiveObserver from _ReactiveCallable
- added preliminary unit tests for hashing (more later)
Fixed the test to better reflect what's happening
Refactoring

- ReactiveObject now uses __slots__ for attributes (faster)
- ReactiveContext private stuff: _objects, _get_caller()
ReactiveContext edits
Fixed hash integrity checking + tests + refactoring
Implemented expression caching (environment hash cache)

- needs more tests though