feature/pkg-config adds libemane pkg-config support

This feature branch adds libemane pkg-config support.

```
 # pkg-config libemane --cflags
-I/usr/include/libxml2 -I/usr/include/uuid
```

```
# pkg-config libemane --libs
-lACE -lrt -ldl -lemane -lxml2 -lprotobuf -lpthread -lpcre -luuid 
````

emane/src/libemane/libemane.pc is automatically generated using configure.ac.

I have tested rpm inclusion but not deb.

```
# rpm -qilp .rpmbuild/RPMS/x86_64/emane-libs-0.9.1-1.fc20.x86_64.rpm 
Name        : emane-libs
Version     : 0.9.1
Release     : 1.fc20
Architecture: x86_64
Install Date: (not installed)
Group       : Libraries
Size        : 1888420
License     : BSD
Signature   : (none)
Source RPM  : emane-0.9.1-1.fc20.src.rpm
Build Date  : Wed 04 Jun 2014 12:26:39 PM EDT
Build Host  : localhost.localdomain
Relocations : /usr 
Packager    : Adjacent Link LLC <labs@adjacentlink.com>
Vendor      : Adjacent Link LLC
URL         : https://github.com/adjacentlink/emane
Summary     : EMANE Libraries
Description :
EMANE Libraries required for components
/usr/lib64/libemane.so
/usr/lib64/libemanexmlparser.so
/usr/lib64/pkgconfig/libemane.pc
/usr/share/doc/emane-libs
/usr/share/doc/emane-libs/AUTHORS
/usr/share/doc/emane-libs/COPYING
/usr/share/doc/emane-libs/ChangeLog
/usr/share/doc/emane-libs/NEWS
/usr/share/doc/emane-libs/PROBLEM-REPORT-FORM
/usr/share/doc/emane-libs/README
/usr/share/doc/emane-libs/SPONSOR
```