Implement infrastructure for simple loci library installation and usage

[dbolotin]

This issue is connected to #42

User story 1 (installation of loci library)

1. If I have a custom loci library and want to use it without specifying the full path I can put it into following locations:
   • PATH_TO_MIXCR_SCRIPT/reference/ for system-wide installation
   • ~/.mixcr/reference/ for user-local installation
   • working directory . or ./reference
2. Symlinks in any of the following cases should be correctly dereferenced by MIXCR

User story 2 (usage of custom loci library)

1. If I have a custom loci library I can use it, either I have installed it or not, in the following way:

   • If it is installed as described above:

     mixcr align --lociLibrary myLL ....
     mixcr assemble ...
     mixcr exportClones ...
     

     I don't have to specify loci library second time in assemble, as *.vdjca file already contains this informatio

   • If I just have a file somewhere in the file system:

     mixcr align --lociLibrary /path/to/myLL ....
     mixcr assemble  --lociLibrary /path/to/myLL ...
     mixcr exportClones  --lociLibrary /path/to/myLL ...
     

User story 2 (default loci library)

1. Any installed libraries with names other than default.ll will be used only if user specified it on the align step, the internal mi.ll will be used if --lociLibrary option is not used.
2. Library installed with the name default.ll will be used by default.