Fix namspaced tag parsing

[CamilleDrapier]

Purpose / Goal

This is a naive attempt at solving the following issue:

#320

Please note that my experience with this repository is fairly low, so I might have missed something important.

Type

Please mention the type of PR

• Bug Fix
• Refactoring / Technology upgrade
• New Feature

Benchmark

Before

Running Suite: XML Parser benchmark
validation : 29237.1202899018 requests/second
xml to json : 24875.297773092963 requests/second
xml to json + json string : 22191.624311589047 requests/second
xml to json string : 3994.622584408293 requests/second
xml2js  : 7993.719125817242 requests/second

After

Running Suite: XML Parser benchmark
validation : 29701.63520998558 requests/second
xml to json : 26255.646131059493 requests/second
xml to json + json string : 22435.547703433473 requests/second
xml to json string : 3904.6532980072416 requests/second
xml2js  : 7286.735343585023 requests/second

NB: benchmarking requires benchmark and xml2js (dev) dependencies that are currently not referenced in package.json

[coveralls]

Coverage increased (+0.03%) to 87.983% when pulling 42554b6 on CamilleDrapier:fix-namspaced-tag-parsing into 4023f6d on NaturalIntelligence:master.