gatt: Add initial support to server write request
gatt: Add result callback for write request
gatt: Support ATT write command

This patch adds support to handling ATT write command PDUs.
squash: Squash to IAS "proximity: Add emitting IAS <<Alert Level>>"
gatt: Support non-const attribute in Read Request

This patch adds support for Read Request to read non-const attributes.
gatt: Add offset parameter to gatt_write_char()

This patch adds an "offset" parameter to gatt_write_char() to allow
the user to write using an offset even when the value is smaller than
the PDU size.
gatt: Introduce attribute write cb for GATT client

This patch adds the callback function to be called when a GATT client
application writes into the attribute value. Its implementation calls
gatt_write_char(), that also handles values that does not fit into a
PDU.
gatt: Implement D-Bus WriteValue

This patch implements the method WriteValue
from org.bluez.gatt.Characteristic1 interface.
gatt: Register Services on server side
gatt: Register characteristic on server side

Register all characteristics and dummies callbacks for read/write.
test: Fix not exporting properties for characteristics

In gatt-service, there was a typo that was causing the Characteristic property
not to exported.
gatt: Validate property for characteristic value at write request

When make ATT operation write request, the bit write from property on
characteristic declaration is considered.
gatt: Add check for characteristic permission to write command

Now the characteristic permission for write is validated when try to
perform a write command.
gatt: Add check for characteristic permission to read request
gatt: Add documentation about byte order

This helps make it clear the expected byte order of "const" attributes.
gatt: Fix methods flags for Characteristic1 iface

ReadValue and WriteValue should have been marked as ASYNC.
gatt: Fix crash when building reply for ReadValue

When a D-Bus message needs to be replied to, the reply message iterator
need to be initialized with dbus_message_iter_init_append(), so the
reply message can be written to.
gatt: Export Characteristic1 properties for clients
gatt: Add a mechanism to store attributes persistently

We store the attributes using a simple GKeyFile file, with the
handle being the group, and Type and Value being the group's fields.
gatt: Add asynchronous Read By Type

This patch extends the Attribute Server adding Ready By Type requests
of asynchronous values: Values defined in a plugin or registered through
the server Generic Attribute API.