Removing mbed-client and other fix commits.

**FEATURE_CLIENT**
Removing FEATURE_CLIENT from mbed-os source tree.

This commit removes FEATURE_CLIENT from mbed-os source tree
Applications using mbed-client now have to explicitly add
mbed-client.lib in addition to mbed-os.lib.

**mbed-client-c**
 -  [v3.0.1](https://github.com/ARMmbed/mbed-client-c/releases/tag/v3.0.1) (15-Sep-2016)
[Full Changelog](ARMmbed/[email protected])

**New features**

- Creates a new sn_nsdl_put_resource function, which takes ownership of sn_nsdl_resource_info_s resource object (not members) instead of creationg copy of it
- Rearranged struct member variable to pack better into memory
- Refactored coap_options_list to treat number members as numbers instead of strings
- Add option to pass incoming blocks to application instead storing them internally
- Added API for deleting one message from resending

**Closed issues:**

- IOTCLT-1001 - mDS does not sent RST anymore for Client after DELETE /subscriptions

**coap-service**
 -  [v4.0.3](https://github.com/ARMmbed/coap-service/releases/tag/v4.0.3) (15-Sep-2016)
[Full Changelog](ARMmbed/[email protected])

**New features**

- Updated coap-service to use new structure from mbed-client-c
- Set link layer security when opening socket.

Author: Yogesh Pande