Don't throw exceptions for (p)connect calls.

When Redis::(p)connect() is called on a newly created Redis instance that will always cause an exception to be thrown. The connect code will actually try and cancel the
exception but this is problematic when you are using tools like APM (pecl.php.net/apm) which hook into the exception handler: it will already have handled it. This change simply stops the connect from throwing exceptions for that situation.
Fix an erroneous unit test failure for TTL

When using the TTL command, Redis >= 2.8 will return -1 for a key
with no TTL and -2 for a key that doesn't exist.  This fixes the
unit tests so they don't expect this in versions < 2.8.
Merge remote-tracking branch 'matmol/dont_throw_exception_on_pconnect' into feature/matmol_connect_ex
Merge in MatMol's changes so we don't throw and then clear an
exception in the context of connect or pconnect

Addresses #361
Merge branch 'feature/matmol_connect_ex' into develop