Bugfixes and improvement of callbacks system

In production (but not in repository) since three months ago.
We have been using a private github repo as dependency. This
change brings this code back to the kurento repo.

Change-Id: I4900919254093814aae573b748601d60e447f3eb
Exporting RpcNotification class

Change-Id: I11c67c56337aa02ca3e20e9c76552b332433b961
Improved comments and using Kurento GitHub repository on package.json

Change-Id: I0f8f0dd8691a194e0e359e97003925f93c1d4495
Added basic tests and fixed info in package.json

Change-Id: I1048a1a00f9301d4c930c4a6150534ba138c438a
Fix README.md and package.json

package.json had a wrong project name.
README.md was inconsistent with kurento standards.
Also, increment version number to kurento standards...

Change-Id: I810ed277dfc116fbec325f42d3e85d09312769bd
[release] Prepare release 4.0.0

Change-Id: Iaf56beb7b5e8001d7379509586375bb58f84cb84
[release] Prepare for next development iteration

Change-Id: Ia059a049e15126b48a0d5102ca268faa3bc5a562
[release] Prepare release 4.1.0

Change-Id: I07fa520f5b3442c9732cf912fac0c75b90e1a37d
[release] Prepare for next development iteration

Change-Id: I87d505d65273a4099f5211ab84cee8985b326e54
[release] Prepare release 4.2.0

Change-Id: I5931c9980db818263c47a694556f95168ffe68be
[release] Prepare for next development iteration

Change-Id: Icf2c46299262e8c62feec5bd95439c80c47b0192
[release] 4.2.1

Change-Id: Ic078c123ccb2a6fa8553c78c2ff73a5682bc66df
[release] Prepare for next development iteration

Change-Id: I80a02d65c983345bd079bd90cc02bc74aa43231c
[release] 4.2.2

Change-Id: I70a778511245f96840cb57ae7cfedbd500f2e5bc
[release] Prepare for next development iteration

Change-Id: If737574be6565384b014b7dfc6e7966748605aab