More operations are supported, specifically creation of serial and
db-generated UUID.

Ints with default values were mistakenly rendred as SERIAL.

Fixes #37

Stop scaffolding ValueGeneratedNever() on keys.

Fixes #16

Fixes #18

* It's now possible to use generate_uuid for server-side UUID
  generation.
* Added an NpgsqlModelValidator that will generate an error if a
  generate_uuid function is used without the uuid-ossp extension.

Closes #2

It's now possible to specify PostgreSQL extensions such as hstore,
postgis on the context. These will be set up in the new database.

Closes #34

Related to #25

Equality test against jsonb in where clauses fails, see #26.

After https://github.com/aspnet/EntityFramework/issues/5215 was fixed

Reacting to https://github.com/aspnet/Announcements/issues/175

To make sure we're rc2-only

Removed runtimes section from project.json, was necessary to get VS
to build. Added <CopyNuGetImplementations> to csproj instead.

dotnet cli build works now, but VS doesn't copy dependent DLLs...
Wait for official RC2 release with VS support.

Project now compiles under VS2015

Note that no tests have been executed and the provider is probably still
broken in some ways (this is just a first step).

Fixes #17

From commit bb43e2282fb13b0deb931d199c95d07ab84169a0.
Project does not compile.