git: Add test-mnclength to .gitignore
gril: Parse correctly signal strength event

The signal strength event was not being parsed properly in the case of
ril v5 parcels.
gril: Changes to prepare for OEM modems

* Add the rild socket path as an input parameter to g_ril_new()
* Remove unneeded ril_s::connected variable
* Implement g_ril_set_disconnect_function()
plugins: Adapt ril to changes in gril interface
Merge pull request #50 from alfonsosanchezbeato/oem-plugin

Some changes to prepare for OEM