Merge branch 'permission-parsing' into 'master'

Parse maxSdkVersion and -23 permission tags

Parse maxSdkVersion and uses-permission-sdk-23 tags and insert them into the index.

AndroidManifest:
```xml
    <uses-permission android:name="android.permission.READ_CALENDAR" />

    <uses-permission
        android:name="android.permission.WRITE_EXTERNAL_STORAGE"
        android:maxSdkVersion="18" />

    <uses-permission-sdk-23 android:name="android.permission.ACCESS_FINE_LOCATION" />
```

new index format:
```xml
<package>
            <version>1.0</version>
            <versioncode>1</versioncode>
            <apkname>maxmin.apk</apkname>
            <hash type="sha256">526eb6d643050c3fae42fb6c001c704006046db52e98998b21f7646ecae3dae5
            </hash>
            <sig>893fc1f22301c902d05c938b29d21648</sig>
            <size>8681</size>
            <sdkver>14</sdkver>
            <targetSdkVersion>24</targetSdkVersion>
            <added>2016-08-01</added>
            <permissions>READ_EXTERNAL_STORAGE,READ_CALENDAR,WRITE_EXTERNAL_STORAGE</permissions>
                <uses-permission name="android.permission.WRITE_EXTERNAL_STORAGE"
                    maxSdkVersion="18" />
                <uses-permission name="android.permission.READ_CALENDAR" />
                <uses-permission name="android.permission.READ_EXTERNAL_STORAGE" />
                <uses-permission-sdk-23 name="android.permission.ACCESS_FINE_LOCATION" />
</package>
```

old format:
```xml
<permissions>READ_CALENDAR,ACCESS_FINE_LOCATION,WRITE_EXTERNAL_STORAGE</permissions>
```

This generates both formats for backward compatibility with old clients.

Also increase version of index format.

This is a proposal for the issues discussed in https://gitlab.com/fdroid/fdroidclient/issues/704

@eighthave @mvdan

See merge request !150

diff --cc fdroidserver/update.py
Simple merge