Provide defaults values for amqp_login

Provide default values for:
 - channel-max as AMQP_DEFAULT_CHANNEL_MAX 0 = unlimited
 - frame-size as AMQP_DEFAULT_FRAME_SIZE 131072 = 128KB
 - heartbeat as AMQP_DEFAULT_HEARTBEAT 0 = disabled
Add compile and runtime library version functions
Adding skeleton of Doxygen documentation
Adding amqp_connect example
Adding documenation on installing rabbitmq-c
Add amqp_connect_uri example

Example shows how to connect using a URI instead of
raw parameters
Stop point
FIX: Add func doc
FIX: amqp_connect*.c compilation issues
More updates