add osgi headers

[tpolecat]

This adds OSGi headers to the jar manifests, which I need downstream to support OSGi in doobie. The end result is that META-INF/MANIFEST.MF now looks like:

Manifest-Version: 1.0 Bnd-LastModified: 1498590525574 Bundle-Description: sourcecode Bundle-ManifestVersion: 2 Bundle-Name: sourcecode Bundle-SymbolicName: com.lihaoyi.sourcecode Bundle-Vendor: com.lihaoyi Bundle-Version: 0.1.4 Created-By: 1.8.0_65 (Oracle Corporation) DynamicImport-Package: * Export-Package: sourcecode;uses:="scala,scala.collection,scala.collectio  n.immutable,scala.reflect,scala.reflect.api,scala.reflect.macros.blackb  ox,scala.runtime";version="0.1.4.SNAPSHOT" Import-Package: scala;version="[2.12,3)",scala.collection;version="[2.12  ,3)",scala.collection.generic;version="[2.12,3)",scala.collection.immut  able;version="[2.12,3)",scala.collection.mutable;version="[2.12,3)",sca  la.math;version="[2.12,3)",scala.reflect;version="[2.12,3)",scala.refle  ct.api;version="[2.12,3)",scala.reflect.internal;version="[2.12,3)",sca  la.reflect.internal.util;version="[2.12,3)",scala.reflect.macros,scala.  reflect.macros.blackbox;version="[2.12,3)",scala.reflect.macros.context  s;version="[2.12,3)",scala.runtime;version="[2.12,3)",scala.tools.nsc;v  ersion="[2.12,3)",scala.tools.nsc.ast.parser;version="[2.12,3)" Require-Capability: osgi.ee;filter:="(&(osgi.ee=JavaSE)(version=1.8))" Tool: Bnd-2.4.0.201411031534 

[tpolecat]

I'm not sure how you do versioning so I bumped it in build.sbt.

[lihaoyi]

I have no clue how OSGI works but you seem like you know what you're doing