ElasticScaleStarterKit: Documentation improvements

We received the below feedback to improve ElasticScaleStarterKit Documentation (located at https://azure.microsoft.com/en-us/documentation/articles/sql-database-elastic-scale-get-started/)
- In prerequisites, add steps to verify whether NuGet is currently installed (a user thought that they had NuGet installed, but they did not, so they received build errors)
- In step 8 of the sample instructions, explicitly tell the user to run task 1 (create shard map and a few shards)
- Under next steps, add links for documentation that shows:
- How to do initial schema deployment
- How to do incremental schema deployment, e.g., adding a column to a table
- How to connect and run a workload, i.e., perform queries, run DML, call sprocs, etc.
- How to use this with SSDT