add client registration to the admin API

Documentation: remove reference to DEX_APP_REDIRECTURL

Fix response_type missing param

This commit fix problem with response_type param, which is required according to OIDC spec, when it is missing.
 At now, when connector_id url query param is not set, connector view use response_type that client request instead of default "code".

Fixes #370

*: remove build-units script

server: add db heatlh checker to server checkers

move outside dependencies to ./vendor directory

Documentation: update roadmap for 0.4 release cycle

closes #328

Fixes #365

server: url decode basic auth credentials

Fixes #336

integration: fix email case sensitivity test

add support for resend an invite email

db: email comparison should be case insensitive

Fix cross compilation

When reading migrations from files, sql-migrate attempts to split
SQL statements. The parsing logic does not handle $BODY$ statements
and broke when the migration included one.

Replace go-bindata with a small migration generation script and use
in memory migrations instead.

Fixes #338