[marytts] Migrate to bnd build

[wborn]

Migrates the MaryTTS Voice add-on to the bnd build.

Some of the MaryTTS packages are split across several JARs which makes it difficult to wrap these as bundles. It also has a lot of dependencies which certainly hasn't improved in newer versions (https://github.com/openhab/openhab2-addons/issues/3953#issuecomment-423659409). 😞

I've also moved the .gitignores for the downloaded libraries to the libs dir so they are automatically moved/deleted on future updates.

log4j-over-slf4j-1.7.21.jar has been removed because it's usage would result in a StackOverflowError. That's probably due to classpath changes causing the ops4j.pax.logging implementations to be picked up:

Caused by: java.lang.StackOverflowError
	at java.util.concurrent.ConcurrentHashMap.get(ConcurrentHashMap.java:936) ~[?:?]
	at org.apache.log4j.Log4jLoggerFactory.getLogger(Log4jLoggerFactory.java:39) ~[?:?]
	at org.apache.log4j.LogManager.getLogger(LogManager.java:45) ~[?:?]
	at org.slf4j.impl.Log4jLoggerFactory.getLogger(Log4jLoggerFactory.java:73) ~[?:?]
	at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:242) ~[6:org.ops4j.pax.logging.pax-logging-api:1.10.1]
	at org.apache.log4j.Category.<init>(Category.java:57) ~[6:org.ops4j.pax.logging.pax-logging-api:1.10.1]
	at org.apache.log4j.Logger.<init>(Logger.java:37) ~[6:org.ops4j.pax.logging.pax-logging-api:1.10.1]
	at org.apache.log4j.Log4jLoggerFactory.getLogger(Log4jLoggerFactory.java:43) ~[?:?]
	at org.apache.log4j.LogManager.getLogger(LogManager.java:45) ~[?:?]
	at org.slf4j.impl.Log4jLoggerFactory.getLogger(Log4jLoggerFactory.java:73) ~[?:?]
	at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:242) ~[6:org.ops4j.pax.logging.pax-logging-api:1.10.1]
	at org.apache.log4j.Category.<init>(Category.java:57) ~[6:org.ops4j.pax.logging.pax-logging-api:1.10.1]
	at org.apache.log4j.Logger.<init>(Logger.java:37) ~[6:org.ops4j.pax.logging.pax-logging-api:1.10.1]
	at org.apache.log4j.Log4jLoggerFactory.getLogger(Log4jLoggerFactory.java:43) ~[?:?]
	at org.apache.log4j.LogManager.getLogger(LogManager.java:45) ~[?:?]
	at org.slf4j.impl.Log4jLoggerFactory.getLogger(Log4jLoggerFactory.java:73) ~[?:?]
	at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:242) ~[6:org.ops4j.pax.logging.pax-logging-api:1.10.1]
	at org.apache.log4j.Category.<init>(Category.java:57) ~[6:org.ops4j.pax.logging.pax-logging-api:1.10.1]
	at org.apache.log4j.Logger.<init>(Logger.java:37) ~[6:org.ops4j.pax.logging.pax-logging-api:1.10.1]
	at org.apache.log4j.Log4jLoggerFactory.getLogger(Log4jLoggerFactory.java:43) ~[?:?]
	at org.apache.log4j.LogManager.getLogger(LogManager.java:45) ~[?:?]

So it now directly uses that log4j logging implementation instead of slf4j.