Use std::unique_ptr to hold pointers to C++ types

Cuts down on cleanup code and fixes a memory leak when creating a shared
group throws an exception.
Build in c++14 mode when building from the pod
clean-up TableView verification
Implement read-only realms

No docs changes because the implementation matches what the docs previously
claimed.

Some assorted design decisions made in the process:

1. refresh and addNotificationBlock are considered "mutating" methods and
disallowed on read-only realms on the grounds that they make no sense.

2. RLMRealm is split into RLMMutableRealm and RLMReadOnlyRealm. This is purely
an implementation detail to slightly simplify the implementation and slightly
improve performance (no checks for the readOnly property). It could be
beneficial to expose this separation in the interface as they do have different
APIs, but I didn't really feel it was worth it.

3. Missing tables in read-only realms are simply treated as if they were empty.
I wanted to make extra columns in tables or missing columns with default values
treated similarly (so that you'd be able to open any realm file that either
matches the schema or can be auto-migrated to the schema), but that'd require
creating separate accessor classes and is far more complexity than it's worth.

4. No attempt is made at handling the case of a read-only RLMRealm in one
process and a mutable RLMRealm in another process sharing a realm file. There's
no easy solution, and more complex solutions (like putting a lock file in /tmp)
should be done in the core and are not very high priority.

5. Realm files must already exist to be openable in read-only mode. Treating a
nonexistent realm as an empty realm is theoretically doable, but would be
awkward (and kinda dumb).
Merge pull request #846 from realm/tg-readonly

Implement read-only realms
support kvc properties when initalizing objects
add test for createInRealm
Merge pull request #864 from realm/al-tv

Clean-up TableView verification
Build the Swift examples project in c++14 mode
pr fixes
Merge pull request #866 from realm/al-kvc

Allow literals to use object with kvc properties
Merge pull request #867 from realm/tg-swift-examples

Build the Swift examples project in c++14 mode
refactored RLMUpdateQueryWithPredicate to only handle NSPredicates
re-add nil predicate check
update RLMPrecondition message
Merge pull request #869 from realm/jp-id-predicate

refactored RLMUpdateQueryWithPredicate to only handle NSPredicates
fix for posible race conditions in tests
Merge pull request #872 from realm/al-race

Fix for posible race conditions in tests
fix for last race condition
Merge pull request #873 from realm/al-race

Fix for last race condition