Changing ConfigureAwait(false) to WithCurrentCulture()

Part of #374
Identity theft made simple...

Add fluent API to set high-level value generation strategy.

Provider-specific API for changing the strategy for a given property still to come. I implemented two methods; open to discussion on combining them and/or different naming idea.
Avoiding blocking on async operations by providing sync counterparts.

Fixes #374
Identity theft for dummies...

Allow SQL Server-specific value generation strategies to be used.

This change adds fluent API for setting Identity or Sequence value generation for integer properties when using SQL Server. Note that Migrations support is still missing--this change only includes a hack to stop Identity columns being generated when sequences are being used.

Currently the default is still Identity. It will be switched to Sequence once Migrations support is added.
fix to issue 691 - we were incorrectly constructing foreign keys by convention in case of composite keys. CR: Arthur
Enabling Built-In Data Types tests for Azure Table Storage. Added a
non-null property to all Built-In data types classes to support having a
PartitionKey and RowId for Azure Table Storage.
Making WithCurrentCulture have the same signature on all platforms allowing it to unify.
U Can't Touch This...

Stop generating values for properties for which a value has been set.

We currently check against the default value for the property type; I will file an issue for allowing this check to be specified, which would then also allow it to be disregarded entirely such that this behavior is switched off.
Fixed the redis case
Add a direct reference to regular expressions.
Added System.Text.RegularExpressions
Added Regex again...
Adding a ValueGenerator to the Redis provider. Moved the common parts of
SqlServerSequenceValueGenerator out into BlockOfSequentialValuesGenerator
and have both SqlServerSquenceValueGenerator and
RedisSequenceValueGenerator inherit from that.
Positive Tests for Negative Cases (adding tests for database error page)
Adding a few end-to-end tests for database error page
Also enabling shared API tests
Making 125 people less mad...

Support store-generated default values

This change allows a property to be marked as using store-generated default values. If no value has been set for the property when the update pipeline inserts the entity the update pipeline will read the value generated from the store. If a value is specified explicitly it will be inserted. This is essentially the same behavior has used for generating keys except that it doesn't involve value generation on Add.

Note that the generation of default constraints in the database by Migrations is not yet implemented so these will need to be setup manually for now.

Also not supported yet is the ability to use this in updates where the semantics are a bit more nuanced.
Updated CancellationToken usage to throw if cancellation is requested before we start the task.
Follow-up to #c2ef45c - now produce context for each test - no need to store
Code cleanup
Added missing dependency
Added reference to tasks in .net 4.5.1 version of SqlServer project