On install, add connection string for elmah

[jayhilden]

When someone installs the nuget package, add the follwoing connection string:

<add name="ElmahElasticSearch" connectionString="Nodes=http://localhost:9200;DefaultIndex=elmah;" />

Also update the configuration section with the correct connection string name including:

1. application name
2. environment name
3. customer name

  <elmah>
    <errorLog
        type="Elmah.Io.ElasticSearch.ElasticSearchErrorLog, Elmah.Io.ElasticSearch, Version=1.0.0.0, Culture=neutral"
        connectionStringName="ElmahElasticSearch"
        applicationName="ElmahElasticSearchSampleWebsite"
        environmentName="development"
        customerName="sample customer"
        />
  </elmah>