Make eunit non-verbose by default

There is no value in a verbose mode for eunit by default because
eunit will print errors of failing tests regardless of what mode
is used. Verbose mode only seem to output what modules are tested
and what tests pass in those modules, in addition to errors.

Disabling verbose will make errors much easier to notice.

README.md

@@ -473,10 +473,9 @@ the test directory specified in `TEST_DIR`.
 
 `EUNIT_OPTS` can be used to specify EUnit-specific options
 (e.g. `verbose`) that will be used when calling
-`eunit:test/2`. This configuration parameter defaults to
-`verbose`. Note
-that EUnit options are specified as a comma-separated
-list of options.
+`eunit:test/2`. This configuration parameter is empty
+by default.. Note that EUnit options are specified as
+a comma-separated list of options.
 
 Relx plugin
 -----------

erlang.mk

@@ -1137,7 +1137,7 @@ TAGGED_EUNIT_TESTS = {dir,"ebin"} $(foreach mod,$(EUNIT_MODS),$(shell echo $(mod
 endif
 endif
 
-EUNIT_OPTS ?= verbose
+EUNIT_OPTS ?=
 
 # Utility functions
 

plugins/eunit.mk

@@ -23,7 +23,7 @@ TAGGED_EUNIT_TESTS = {dir,"ebin"} $(foreach mod,$(EUNIT_MODS),$(shell echo $(mod
 endif
 endif
 
-EUNIT_OPTS ?= verbose
+EUNIT_OPTS ?=
 
 # Utility functions