Random "Error getting queue payload" in RedisQueue under load

[Seadoo2017]

After recent package update we started getting this error message, we tracked the issue down to a change done in RedisCacheClient.
All the read operations now use CommandFlags.PreferReplica (changed in this commit: 8ea1bf1)

Sometimes, the replica might not have the data when a read operation is performed right after write operation.
So this cache change breaks RedisQueue randomly.

My suggestion is to revert the change or allow injecting the required behavior.

[ejsmith]

Would you mind creating a PR that adds a read mode to the redis options? So we can set it to PreferReplica or PreferMaster.

[Seadoo2017]

Hi, added pull request (#81)
I added read mode to options + reverted the default behavior to none as the new behavior is breaking existing code.
Due to the nature of this issue, I didn't think of any good way to add unit test to test this change / demonstrate the breaking change in unit test, any ideas?

I gave access in the option to the original CommandFlags with all the available options to have full flexibility, do you prefer a new smaller enum / boolean option?

Thank you.

[Seadoo2017]

@ejsmith I apologize but I had to open a new PR (#82) because I messed up the author at the first one so it didn't let me sign the CLA, this one is the same with the correct author.