Support more parameters when creating deployments

[sandhose]

The DeploymentRequest object has a few more parameters that could be exposed. In my case, I'd like to set the AutoMerge property. Looking at the code it shouldn't be that hard to do.

[ahume]

@sandhose Thanks for reporting/requesting this.

PR for supporting AutoMerge: #17

Would appreciate input regarding only setting it when the input string is false. Does this seem sensible? Includes a wider change refactoring OutParams, which simplifies this.

Will add support for other parameters in different PRs.