reduce external packages size

[stdweird]

currently the icommands packages depend on the the externals packages which are huge (eg boost is 160MB; of which 120MB of header files, and small amount of .a files).

there are 2 (or even more) ways to fix this:

• generate the "regular" externals rpm with only the lib*/*so files (and nothing else; in fpm, only use lib dir and exclude *.a) and generate a 2nd rpm (with -devel suffix to the name), that ships the rest (current build, but exclude lib*/*so). that way the regular external rpms are very light, and people can still install the full development packages; and this should be easy in the bulld.py (not sure how to set the dependency of the devel packages to the regular ones though)
• same as before, but give the minimal packages a different name, and change the package dependencies of the commands packages to these runtime packages

however, as i am unfamiliar with irods, i don't know if rules need the development files to "compile".