Add 'Fragment-Host' to submodules for OSGi

Based on discussion on issue https://github.com/Netflix/RxJava/issues/154
Merge pull request #186 from benjchristensen/issue-154-osgi

Add 'Fragment-Host' to submodules for OSGi
Confusing Javadoc for `toObservable(Future)` methods

https://github.com/Netflix/RxJava/issues/148
Merge pull request #187 from benjchristensen/issue-148

Confusing Javadoc for `toObservable(Future)` methods
Version 0.6.0

This release includes some small breaking changes to the API.
Subscriptions cleanup

- make createSubscription be create … as I had originally intended to do but forgot to
- make EmptySubscription a singleton
update clojure and groovy code to subscriptions changes
Merge pull request #188 from benjchristensen/issue-173

Subscriptions cleanup
0.6.1-SNAPSHOT
Note on versioning on road to 1.0
gracefully handle null subscription on trusted onSubscribe the same as non-trusted already does
add try/catch in example to better demonstrate error handling

… despite no errors being possible of being thrown in this code
more thorough error handling in case Func1 implementation itself fails

- Func1.call may fail (null impl, bad impl, etc)
- Func1.call may success but the implementation itself may throw an exception instead of properly catching and sending to onError
Merge pull request #189 from benjchristensen/polishing

Handful of Improvements
updates dematerialize so can chain correctly
Merge pull request #190 from prabirshrestha/chainDematerialize

update dematerialize so can chain correctly
Version 0.6.1
implemented OperationWhere
added where operation to Observable
Add pointer regarding unit tests as inner classes