Provide better error message when metadata files are missing in *.apk file

[Fatme]

Currently NativeScript for Android runtime crashes with the following cryptic error when cannot find metadata files

F/libc    (13462): Fatal signal 11 (SIGSEGV), code 1, fault addr 0x28 in tid 13462 (vescript.myAppG)
I/DEBUG   (  204): *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
I/DEBUG   (  204): Build fingerprint: 'google/volantis/flounder:5.1.1/LMY47X/1849464:user/release-keys'
I/DEBUG   (  204): Revision: '0'
I/DEBUG   (  204): ABI: 'arm'
I/DEBUG   (  204): pid: 13462, tid: 13462, name: vescript.myAppG  >>> org.nativescript.myAppG <<<
I/DEBUG   (  204): signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr 0x28
I/DEBUG   (  204):     r0 f75e57bc  r1 00000001  r2 00000002  r3 ffffff4c
I/DEBUG   (  204):     r4 00000000  r5 ff7fff60  r6 00000002  r7 f75d9600
I/DEBUG   (  204):     r8 e36d20d8  r9 00000000  sl ab443894  fp ff7ffdc4
I/DEBUG   (  204):     ip f75d9d9c  sp ff7ffce8  lr e3290543  pc f75b76cc  cpsr 20070030
I/DEBUG   (  204): 
I/DEBUG   (  204): backtrace:
I/DEBUG   (  204):     #00 pc 000356cc  /system/lib/libc.so (fseeko+27)
I/DEBUG   (  204):     #01 pc 0024b53f  /data/app/org.nativescript.myAppG-1/lib/arm/libNativeScript.so (tns::NativeScriptRuntime::BuildMetadata(tns::JEnv&, _jstring*)+122)
I/DEBUG   (  204):     #02 pc 002477e3  /data/app/org.nativescript.myAppG-1/lib/arm/libNativeScript.so (PrepareV8Runtime(v8::Isolate*, tns::JEnv&, _jstring*, _jstring*)+1258)
I/DEBUG   (  204):     #03 pc 00247f43  /data/app/org.nativescript.myAppG-1/lib/arm/libNativeScript.so (Java_com_tns_Platform_initNativeScript+182)
I/DEBUG   (  204):     #04 pc 000ef68d  /data/dalvik-cache/arm/data@app@org.nativescript.myAppG-1@base.apk@classes.dex

[atanasovg]

Related to #221

[Plamen5kov]

fixed with #277