gatt: Fix memory leak when creating descriptor
core: Fix reply for Pair

This patch fixes the missing D-Bus Pair Request reply.
gatt: Remove leftover primary service code

This patch removes primary service list. GATT services over BR/EDR
was broken already and it needs to be fixed later.
FIXUP: gatt: Fix potential invalid memory access

Fix invalid read:

==765== Invalid read of size 4
==765==    at 0x80D0932: read_request_result (gatt.c:2207)
==765==    by 0x80CFE9E: read_name_cb (gatt.c:1879)
==765==    by 0x80D0CB9: read_request (gatt.c:2277)
==765==    by 0x80D17B7: channel_handler_cb (gatt.c:2605)
==765==    by 0x80A5B48: received_data (gattrib.c:422)
==765==    by 0x40BD17D: g_io_unix_dispatch (giounix.c:166)
==765==    by 0x407CD85: g_main_context_dispatch (gmain.c:2539)
==765==    by 0x407D124: g_main_context_iterate.isra.21 (gmain.c:3146)
==765==    by 0x407D56A: g_main_loop_run (gmain.c:3340)
==765==    by 0x41BB4D2: (below main) (libc-start.c:226)
==765==  Address 0x45dc828 is 0 bytes inside a block of size 8 free'd
==765==    at 0x402AF79: free (vg_replace_malloc.c:446)
==765==    by 0x4082D0A: standard_free (gmem.c:98)
==765==    by 0x80CFE9E: read_name_cb (gatt.c:1879)
==765==    by 0x80D0CB9: read_request (gatt.c:2277)
==765==    by 0x80D17B7: channel_handler_cb (gatt.c:2605)
==765==    by 0x80A5B48: received_data (gattrib.c:422)
==765==    by 0x40BD17D: g_io_unix_dispatch (giounix.c:166)
==765==    by 0x407CD85: g_main_context_dispatch (gmain.c:2539)
==765==    by 0x407D124: g_main_context_iterate.isra.21 (gmain.c:3146)
==765==    by 0x407D56A: g_main_loop_run (gmain.c:3340)
==765==    by 0x41BB4D2: (below main) (libc-start.c:226)
==765==
todo: Add GATT over BR/EDR
gatt: Remove unneeded ATT connected checking

Caller should check if ATT channel is established on not before calling
the connect function.
gatt: Fix memory leak in GATT plugin

This patch fixes a memory leak of the attribute list when the profile
is probed.
gatt: Add value, vlen and offset fields to attr_write_data struct
gatt: Implement write characteristic callback on server side

It allows write dynamic attributes on external services. The D-Bus
method WriteValue is called on an external service. After the reply
from the external service, the btd_attr_write_result_t will also be
called.
test: Add SIGINT/SIGTERM handler for gatt-service

This allows to cleanly shutdown and detect resource leaks.
test: Split service and characteristic interface registration
test: Support multiple services in gatt-service

Allow to customize Service and Characteristic parameters and register
multiple services.
test: Implement Link Loss Service in gatt-service
gatt: Create one GDBusClient per application

The GDBusClient implementation expects a single instance for each
application.
gatt: Add timer to register services/characteristics